Chinese Air-Launched Passive Anti-Radiation Missiles (Report Preview)

Note: The following text is part of a forthcoming SPAS Consulting Report examining the strengths and limitations of China's long-range conventional strike capabilities.

A Brief History of Anti-Radiation Missile Technology Development

The advent and progressively increasing range of radar-guided surface-to-air missiles in the early Cold War posed a major challenge to aircraft designers. In time, combat aircraft were equipped with passive radiation homing anti-radiation missiles to undertake not only standoff attacks on previously detected radar-guided surface-to-air missile systems but also reactive standoff attacks on previously undetected surface-to-air missile systems. The United States was the pioneer in this area of technology, having deployed the supersonic AGM-45 Shrike, which is derived from the AIM-7 Sparrow air-to-air missile, in the 1960s. The United States later deployed the more capable supersonic AGM-78 Standard, which is derived from the RIM-66 Standard naval surface-to-air missile, in the late 1960s, and a much more capable purpose-built design, the supersonic AGM-88 HARM, in the mid-1980s. The latest versions of the four-decade-old HARM design family, the AGM-88E AARGM, and its longer-range derivative, the AGM-88G AARGM-ER, constitute international benchmarks for performance in this area of technology.

Notably, these American anti-radiation missile designs, all of which are powered by solid-fuelled rocket motors, are small and light enough to be employed by fighter aircraft and similar. It bears emphasis that most combat aircraft deployed by the end of the Cold War, including those operated by the United States and other NATO countries, were not truly multi-role designs when it came to the employment of guided as opposed to unguided air-to-ground munitions. Most Cold War American combat aircraft did not employ the aforementioned anti-radiation missiles. The task of suppressing adversary air defences with anti-radiation missiles was instead heavily concentrated in a small subset of specially configured American combat aircraft operated by aircrews that received specialized training.

The Soviet Union followed the American lead in anti-radiation missiles but was a laggard in this area of technology until the final years of the Cold War. The Soviet Union first developed the Kh-22P, an anti-radiation missile version of the Kh-22 liquid-fuelled rocket-powered supersonic anti-ship missile. The Kh-22P is so large and heavy that it can only be carried by bomber aircraft. In the 1970s, the Soviet Union deployed a much smaller and lighter anti-radiation missile, the liquid-fuelled rocket-powered supersonic Kh-28, for use by fighter aircraft and similar. The Kh-28 was succeeded by the more capable solid rocket-powered supersonic Kh-58 in the early 1980s. It was not until the final years of the Cold War that the Soviet Union came close to closing the gap in the area of anti-radiation missile technology with the introduction of the ramjet-powered supersonic Kh-31P.

The Cold War came to a close before the Kh-31P, which was developed for use by the latest Soviet combat aircraft designs, could be built in large numbers, let alone widely deployed by the Soviet Union’s decidedly heterogeneous and increasingly aging fleet of combat aircraft. It bears emphasis that most combat aircraft deployed by the end of the Cold War, particularly those operated by the Soviet Union let alone those of resource-poor Warsaw Pact countries that lagged even further behind in terms of the technological frontier, were not multi role designs when it came to the employment of guided as opposed to unguided munitions. Most of the combat aircraft in the decidedly heterogeneous and aging fleet collectively deployed across the Soviet Air Force, Soviet Air Defence Forces, and Soviet Naval Aviation were incapable of launching anti-radiation missiles of any type. The Kh-58 and the Kh-31P were, therefore, specialized munitions employed by a subset of specially configured Soviet combat aircraft and associated aircrews that received specialized training. This included highly specialized aircraft such as the rare MiG-25BM, a version of the MiG-25 high-speed interceptor configured to launch four supersonic Kh-58 anti-radiation missiles.

The Sino-Soviet Split cut China off from international developments in anti-radiation missile technology as it did in most areas of military technology. While China was indirectly exposed to anti-radiation missile technology as a result of the widespread employment of such munitions by the United States against North Vietnam’s Soviet- and Chinese-supported air defences, China’s resource limitations, the limitations of China’s military industry, and the domestic turmoil that China experienced following the Sino-Soviet Split left the PLAAF in no position to even attempt to catch up in the fast-changing area of anti-radiation missile technology. 

The PLAAF, which was heavily reliant on a fleet of Soviet-designed J-5 (MiG-15), J-6 (MiG-19), and the J-7 (MiG-21) light fighters throughout the Cold War, also lacked suitable aircraft for the employment of anti-radiation missiles even if a functioning design was available. As a result, the PLAAF’s experience with anti-radiation missile technology did not begin until the early 2000s following the deployment of a modestly sized fleet of new-build Soviet-Russian Su-30MKK multi-role fighters. The weapons package for the PLAAF’s procurement of the Su-30MKK included the Soviet-Russian ramjet-powered Kh-31P anti-radiation missile. Although the PLAAF was several decades late to adopting anti-radiation missiles, doing so in the early 2000s as part of an expansive long-term modernization effort meant that the PLAAF of the 2010s was better positioned to equip anti-radiation missiles on a larger portion of its steadily growing fleet of multi role combat aircraft fleet than was the case with the United States and Soviet Union until the final decade of the Cold War.

YJ-91 (Kh-31P) Passive Radiation Homing Anti-Radiation Missile

While China imported the Soviet-Russian Kh-31P anti-radiation missile from the Russian production line for use with the Su-30MKK multi-role fighter, Russia appears to have agreed to technology transfer and the establishment of a separate production line in China. This amounts to an important data point for the PLAAF’s long-term ambitions as of the late 1990s and the early 2000s. The Chinese-built versions/derivatives of the Soviet-Russian Kh-31P anti-radiation missile are known by the Chinese designation YJ-91. The YJ-91 has presumably been built in multiple production configurations over the past two decades or so. Externally, the YJ-91 is largely indistinguishable from the Kh-31P and appears to be primarily differentiated in terms of electronic components – including the all-important passive radiation homing seeker – and associated software that are concealed within the airframe. Limited information is publicly available about the passive radiation homing seeker, or seekers, installed or available for installation in the YJ-91. Although the Kh-31P was integrated with the Soviet-Russian Su-27/Su-30 family of fighter aircraft, the YJ-91 is widely deployed across the PLAAF’s combat aircraft fleet, including the Chinese-designed and built J-10 fighter family. 

The YJ-91/Kh-31P is a large missile that weighs around 600 kg. The air-breathing ramjet engine, which employs liquid fuel and draws oxygen from the atmosphere, powers the YJ-91 to a maximum speed of around Mach 3 over a reported nominal maximum range of 110 km while equipped with an 87 kg warhead. Ramjet engines do not function at low airspeeds. The YJ-91, therefore, relies on an integral solid rocket booster to accelerate the YJ-91 to a speed suitable for ignition of the ramjet engine. The maximum practical range of the YJ-91 is affected by its flight profile. All else being equal, range can be maximized with a higher-altitude flight profile that minimizes the time-distance spent at lower altitudes. As with any air-launched munition, the maximum practical range of the YJ-91 is also affected by the speed and altitude of the host aircraft at the time the munition separates from the host aircraft. 

Although the ramjet-powered YJ-91/Kh-31P has a higher top speed and carries a larger warhead than the American solid-fuelled rocket-powered HARM family of anti-radiation missiles, the Chinese versions of this Soviet-Russian design have a decidedly lower maximum range than the latest versions of the American HARM family, the AGM-88E AARGM and its extended-range derivative, the AGM-88G AARGM-ER. American designers develop air-launched munitions for use by combat aircraft that are intended to operate in the face of long-range surface-to-air missile systems such as the Russian S-300/S-400 family and the Chinese HQ-9 family. As a result, American designers increasingly place a premium on maximum range in air-launched munitions as this is the only practical way of undertaking a medium- let alone a high-altitude standoff attack with an anti-radiation missile against a long-range surface-to-air missile system short of the widespread deployment of robust all-aspect low signature aircraft designs. 

While the electronics and software installed in the latest production versions of the YJ-91 are likely to be very different than the those integrated into the Russian-built Kh-31P missiles that China imported in the early 2000s for use with the Su-30MKK, there is no indication that the YJ-91 has undergone a comparable evolution to the American HARM family over the past two decades or so even in a context in which the American Patriot and the Taiwanese Tien Kung III (TK-3), the two primary land-based long-range surface-to-air missile systems that the PLAAF encounters in the Western Pacific, considerably outrange the YJ-91 even when the Chinese version(s) of this Soviet-Russian anti-radiation missile design are launched from a high altitude. 

It bears emphasis that the Kh-31P was developed to meet very specific Soviet requirements that existed a military-geographical context in which (A) low altitude ingress over land toward the target was an option and (B) short- and medium-range surface-to-air missile systems posed a greater threat to the launch aircraft than long-range surface-to-air missile systems, which face line-of-sight restrictions and aircraft flying and medium let alone low altitudes, and which were more expensive and therefore less widely deployed close to the borders of the Warsaw Pact even in the final years of the Cold War. The PLAAF of early 2025, in contrast, operates in a military-geographical context in which its combat aircraft are exposed to adversary combat aircraft and long-range surface-to-air missiles when operating over water, let alone over adversary-controlled territory. The YJ-91 anti-radiation missile is, therefore, of diminishing utility as the threat posed to PLAAF combat aircraft carrying the YJ-91 increases.

Although there is scope for improving the performance of the YJ-91 – the Russian manufacturer’s latest version, the Kh-31PD, has a claimed nominal maximum range of 250 km – the inherited Soviet ramjet-powered design imposes constraints, and the YJ-91/Kh-31 airframe’s large size and weight inhibit current and future PLAAF operations. These negative effects will only increase as PLAAF operations increasingly focus on the J-20, J-35, and other crewed and uncrewed combat aircraft designs in which munitions are primarily, if not exclusively, carried in internal weapons bays of finite volume. There is, moreover, no indication that China has developed a version of the YJ-91 that approaches the latest Russian Kh-31PD in terms of maximum range.

It is worth noting that China's military industry offers the LD-10, a passive radiation homing anti-radiation missile derived from the PL-12 air-to-air missile in the same manner that the American AGM-45 Shrike was derived from the AIM-7 Sparrow air-to-air missile. Although the LD-10 amounts to a smaller, lighter, and shorter-range alternative to the YJ-91, public sources offer no indication that the LD-10 has been adopted and deployed by the PLAAF or PLANAF. The PL-12 has also been supplanted by the longer-range PL-15 air-to-air missile in PLAAF service and the PL-15 is, therefore, a more likely candidate for adaptation into a passive radiation homing anti-radiation missile provided that the PLAAF decides against procuring a clean sheet long-range anti-radiation missile design in the vein of the latest American AGM-88G AARGM-ER. 

In 2020, observers may have received a glimpse into the future of the PLAAF’s anti-radiation missile capabilities. A possible anti-radiation missile design of unknown designation was pictured mounted on the wings of a two-seat J-11BS fighter aircraft, which may have been employed to facilitate the flight testing of the blue-coloured – inert – missile specimens loaded onto the aircraft. This possible anti-radiation missile of unknown designation does not have a design indicative of ramjet propulsion and may be related to the export-oriented solid-fuelled rocket-powered CM-102.

The CM-102, which competes with the LD-10 for international orders, is a supersonic anti-radiation missile with a reported nominal maximum range of 100 km while equipped with a reported 80 kg warhead. The CM-102 is, as such, something of an analogue to earlier non-extended-range members of the American HARM design family. It bears emphasis that air-to-air missiles tend to have a small – and highly specialized – warhead that weighs no more than 20-40 kilograms. Anti-radiation missiles derived from air-to-air missiles like the aforementioned export-oriented LD-10, therefore, have a limited destructive radius and must register a high accuracy impact on the target radar. The possible anti-radiation missile design of unknown designation seen on a J-11BS fighter in 2020 is not identical to the CM-102 mockups displayed at military industrial exhibitions and may have a substantially greater range than the CM-102 or, more to the point, the YJ-91 anti-radiation missile. 

Uncertainties about the possible unheralded deployment of one or more new anti-radiation missile designs notwithstanding, it is possible the PLAAF views the YJ-91, which may remain in production as of 2025, as a stop-gap system pending the availability of a suitable scramjet-powered air-launched cruise missile design and/or an air-launched ballistic missile design. Such high-speed munitions with a low time to target do not necessarily require an onboard passive radiation homing seeker to target actively emitting radars and surface-to-air missile systems. It is also possible that the PLAAF has deployed an extended range version of the YJ-91 that is similar to the latest Russian Kh-31PD. Although an extended range version will make the YJ-91 a more practical and likely more effective anti-radiation missile for the PLAAF, it will remain a large and heavy air-launched munition that can be carried in very limited numbers by most combat aircraft designs. The YJ-91 anti-radiation missile is likely to be far too cumbersome for internal carriage on the J-20, J-35, and forthcoming Chinese low-signature crewed and uncrewed fixed-wing combat aircraft designs. 

The YJ-91/Kh-31P air-launched anti-radiation missile can be employed by 44.78% of the combined fleet of ~2200 non-bomber crewed fixed-wing combat aircraft reportedly deployed by the PLAAF and PLANAF in early 2025. The integration of the YJ-91A/Kh-31A anti-radiation missile has confirmed with the JH-7A strike aircraft (x4), J-10C multirole fighter (x2), J-15 STOBAR multirole fighter (x2), J-15T CATOBAR multirole fighter (x4), and J-16 multirole fighter (x6).

Other Aerial Munitions Optimized to Target Surface-to-Air Missile Systems and Acquisition Radars

Supersonic anti-radiation missiles, whether rocket- or ramjet-powered, are desirable because high speed amounts to a short time-to-target. There are, however, other types of aerial munitions equipped with passive radiation homing seekers that can be used to target surface-to-air missile systems and acquisition radars. Observers should not, as such, simply compare the reported specifications of the Chinese YJ-91 anti-radiation missile with those of members of the American HARM family. With supersonic anti-radiation missiles amounting to the archetype for this area of military technology, it is productive to briefly examine the history of anti-radiation missile development before examining other anti-radiation missiles and related air- and surface-launched munitions deployed by the PLAAF. 

For the American designers that were pioneers in this area of technology, a short time-to-target was particularly valuable when it came to targeting the highly mobile – both wheeled and tracked – self-propelled medium- and short-range surface-to-air missile systems that were widely deployed by the Soviet Army and the Warsaw Pact. Highly mobile Soviet surface-to-air missile systems could not only quickly cease radar emissions that passive radiation homing seekers – in the absence of INS and GNSS guidance to target the last known location of the hitherto emitting radar – would home in on, but could also relocate within minutes and thereby escape the destructive radius of a slower subsonic anti-radiation missile with a far longer time to target.

The use of supersonic anti-radiation missiles not only eroded the benefits of mobility in a surface-to-air missile system but also incentivized the operators of surface-to-air missile systems to forgo constant emissions and, no less importantly, to cease emissions as soon as possible when encountering a strike package in which some aircraft were likely to be equipped with a supersonic short time-to-target anti-radiation missile. With short-, medium-, and long-range surface-to-air missile systems typically reliant on semi-active radar homing guidance – which requires the target aircraft to be painted or illuminated by an engagement radar for the receive-only antenna on the surface-to-air missile to home in on a target aircraft – through the end of the Cold War, supersonic anti-radiation missile launches could significantly degrade the effectiveness of surface-to-air missiles already in flight unless the operators of a surface-to-air missile system did not cease emitting by powering down the radar and/or attempting to relocate, which is to say unless the operators of a surface-to-air missile system decided to fight it out and risk being struck by one or more inbound supersonic anti-radiation missiles.

The approach to suppressing air defences with supersonic anti-radiation missiles pioneered by the American military has always had clear-cut strengths but has never been the only approach available to air forces. Supersonic anti-radiation missiles like the American HARM family have multiple operating modes that vary in terms of reliance on external sensor data and the installation of equipment to detect and process radar emissions on the host combat aircraft. Although anti-radiation missiles can be integrated onto a large number of combat aircraft designs, specially configured aircraft operated by aircrews with additional specialized training are required to make full use of the capabilities of anti-radiation missiles like the HARM family. In the United States, the employment of supersonic anti-radiation missiles was associated with small and highly specialized fleets of specially configured aircraft operated by aircrews with additional specialized training until the late 1990s. Such aircraft, which were called Wild Weasels in the parlance of the U.S. Air Force, are very expensive to build/convert and operate and are therefore available in limited numbers. 

In the U.S. Air Force, the Wild Weasel suppression of air defences mission was first undertaken by specialized F-105F fighter-bombers and later the highly specialized F-4G fighter. While it was complemented by a relatively small number of unarmed EF-111A Raven electronic warfare aircraft that entered service in the 1980s, the F-4G remained the U.S. Air Force’s primary asset for the suppression of air defences until the end of the Cold War and was heavily employed in the Gulf War. The F-4G fleet was retired by the late 1990s as was the unarmed EF-111A. The suppression of air defence mission was thereafter divided between the U.S. Navy (and U.S. Marine Corps), which operated a sizable fleet of carrier-borne EA-6B Prowler electronic warfare aircraft (later replaced in service by the U.S. Navy’s EA-18G Growler) and the U.S. Air Force’s F-16CJ/DJ Block 50/52 aircraft, which were delivered from the early 1990s onward. While the F-16CJ/DJ is not specially equipped in the manner of the F-4G and remains a multirole fighter aircraft, it is equipped with the AN/ASQ-213 HARM Targeting System, which was not standard equipment on the other F-16 variants built up to that time, and thereby became the de facto replacement for the F-4G.

Following the Cold War, the U.S. Air Force and other NATO air forces undertook sweeping mid-life upgrade programs that adapted the likes of the F-16 fighter, which first entered service in 1980 as a day fighter, into veritable multirole combat aircraft equipped with a wide range of guided air-to-ground munitions including the AGM-88 HARM anti-radiation missile. This was an important development because no other NATO country, including existing operators of the underlying F-4 Phantom, operated the F-4G, let alone the more complex, more sensitive, and much more expensive unarmed EF-111A electronic warfare aircraft. As a result, NATO countries interested in the AGM-88 HARM could not take full advantage of the capabilities offered by this American supersonic anti-radiation missile design – the earlier AGM-45 Shrike and AGM-78 Standard were not exported to other NATO countries. The only partial exception to this dynamic during the Cold War were the air forces of West Germany and Italy, which ordered the more complex and more expensive Tornado ECR, a version of the Tornado IDS strike aircraft configured to suppress air defences through the employment of the AGM-88 HARM in the manner of the F-4G. The Tornado IDS was, however, only deployed in the 1990s and was always intended to complement the West German and Italian Tornado IDS strike aircraft fleets in small numbers. 

Other NATO countries were, of course, also interested in suppressing Soviet and Warsaw Pact air defence systems and pursued different approaches than the archetypal approach exemplified by the supersonic fire-and-forget American AGM-88 HARM design family. In the 1970s, France and the United Kingdom jointly developed the Martel. A subsonic design powered by a solid rocket motor in the manner of the rocket-powered anti-ship cruise missiles of its era, the Martel was available in a human-in-the-loop version equipped with TV guidance as well as a fire-and-forget version equipped with a passive radiation homing seeker. The passive radiation homing seeker-equipped version of the subsonic Martel, which was only deployed by the United Kingdom, was intended for use against both radar-equipped warships and ground-based air defences. Employment of the subsonic Martel did not require the use of specially configured aircraft or aircrews with specialized training. A supersonic anti-radiation missile was not, in other words, the only approach that militaries could pursue. 

Following the joint development of the Martel, France and the United Kingdom parted ways and pursued different approaches for their next-generation anti-radiation missile designs. In the late 1970s, France developed the fire-and-forget ARMAT subsonic solid-fuelled rocket-powered missile equipped with a passive radiation homing seeker on the basis of the earlier Martel. Like its predecessor, the ARMAT had a major limitation that affected all subsonic anti-radiation missile designs. A subsonic cruise speed – slow time-to-target – means that subsonic anti-radiation missiles are not well suited for reactive launches (i.e., in a self-defence mode) and are primarily intended to attack pre-identified stationary targets such as the fixed and semi-mobile long-range acquisition radars that constitute the core of most countries' early warning radar networks. With a time-to-target of around seven minutes to its nominal maximum range, the subsonic fire-and-forget ARMAT was wholly unsuited for use against the highly mobile wheeled and tracked self-propelled medium- and short-range surface-to-air missiles systems deployed in large numbers by the Soviet Army and other Warsaw Pact militaries. At the same time, employment of the ARMAT did not require the use of specially configured aircraft or aircrews with specialized training.

Whereas France was content with not allocating the resources required to expand the technological frontier, the United Kingdom pursued a different approach. The British Air Force did not want to procure and operate a fleet of specially configured aircraft like the F-4G or Tornado ECR operated by aircrews with specialized training. It was instead interested in a passive radiation homing anti-radiation missile that could be launched from essentially any combat aircraft in its fleet. Given this requirement, the American AGM-88 HARM was not a practical option, and the United Kingdom instead developed the ALARM anti-radiation missile, which was deployed in the 1980s. Like the earlier British-French Martel and the French ARMAT, the supersonic – not subsonic – ALARM was a powered by a solid rocket motor but had a unique design feature that it employed on one of its operating modes: the ALARM was designed to loiter over an area before attacking a target identified by its passive radiation homing seeker. This allowed the ALARM to target radar-guided surface-to-air missile systems and acquisition radars that ceased emissions while under attack by possible anti-radiation missiles. 

Ordinarily, solid rocket motors and loitering are a contradiction in terms – solid rocket motors burn for a time frame of mere seconds, and loitering is irrelevant unless measured in minutes, if not hours. The use of a solid rocket motor in the ALARM and other missiles inhibited sustained flight without a steady loss of altitude. When employed in the loitering mode, the ALARM missile was launched to a high altitude, and a parachute was released after the rocket had burned out. With its rate of descent slowed by the parachute, the passive radiation homing seeker monitored the area within its (limited) field of view for radar emissions. Once a suitable target was detected, the missile was released from the parachute and dived toward the detected emitting radar with the aid of a secondary solid rocket booster. This is an entirely different mode of operation than that associated with the American AGM-45, AGM-78, and AGM-88, as well as the Soviet Kh-28, Kh-58, and Kh-31 (i.e., the Chinese YJ-91).

Aside from its unique loitering operating mode, the British ALARM loitering anti-radiation missile was a remarkably small and light design with a launch weight of less than 300 kg. This allowed British combat aircraft – none of which were specially configured or operated by air crews with specialized training in the manner of the F-4G or Tornado ECR (the British Air Force operated the Tornado IDS and Tornado ADV in large numbers) – to readily carry multiple ALARM anti-radiation missiles per sortie without having to forgo the use of multiple weapons stations for other munitions and payloads. Carrying the American AGM-88 HARM, let alone the much larger and heavier Soviet Kh-58 and Kh-31, in contrast, has a significant effect on the capacity of the host aircraft to carry other munitions and payloads. 

Given its unique mode of operation, the British ALARM, which, of course, had a limited loitering time while the parachute was deployed, was better suited to suppressing air defences – incentivizing operators to cease emissions and/or relocate – than necessarily damaging or destroying air defences in the manner of a supersonic anti-radiation missile with an very short time-to-target. The mere existence, let alone launch, of a supersonic anti-radiation missile like the AGM-88, however, only disincentivizes the operation of air defences for a brief time – a launch aircraft has a limited loiter time and can only carry a few AGM-88 missiles. The ALARM, in contrast, not only facilitated the suppression of air defences over a longer time frame but could also be launched in large numbers as a result of its small size and lighter weight. The likes of the ALARM loitering anti-radiation missile, therefore, offer a capability and effect that supersonic anti-radiation missiles cannot.

These variant experiences with anti-radiation missile technology, particularly the British ALARM, underscore the fact that although supersonic anti-radiation missiles like the American HARM family constitute an archetype, there are a range of, all else being equal, non-exclusive approaches that the PLAAF can undertake to target surface-to-air missile systems and acquisition radars with its fleet of combat aircraft. That said, the British ALARM had major limitations and is unlikely to constitute a template for what the PLAAF may pursue if not already deploy. The solid-fuelled rocket-powered ALARM is not, of course, a true loitering missile – the use of a parachute has the effect of converting an ALARM from a rocket-powered cruise missile into a parachute retarded-turned-rocket-boosted bomb. The mode of operation of the ALARM is also reflective of a time before INS and GNSS – which allow an anti-radiation missile to target the last known location of a radar that has promptly ceased to emit – became widely available. During the Cold War, it was the United States that developed the first true loitering anti-radiation missile, the AGM-136 Tacit Rainbow.

The U.S. Air Force understood the merits of a loitering anti-radiation missile to complement – not replace – the short time-to-target supersonic AGM-88 HARM missile. The ultimately unsuccessful design it selected for procurement, the fire-and-forget AGM-136, was an air-launched subsonic winged cruise missile powered by an air-breathing turbofan engine with a target nominal range of over 400 km. Developed in the 1980s and intended for carriage by both fighter and bomber aircraft, the subsonic AGM-136 was designed to loiter over a preprogrammed area until the onboard passive radiation homing seeker detected a suitable target, after which the AGM-136 would plot a trajectory to detonate on impact with the intended target. 

Whereas the British ALARM constituted, all things considered, a briefly lingering threat to Soviet and Warsaw Pact air defences, the AGM-136 amounted to a truly persistent threat and offered a capability that cannot be matched by any supersonic anti-radiation missile design. The American AGM-136, as such, amounted to perhaps the ultimate countermeasure to the very unique threat posed by the highly mobile wheeled and tracked self-propelled medium-range and short-range surface-to-air missile systems that were deployed in very large numbers by the Soviet Army. It bears emphasis that the highly mobile air defence systems operated by the Soviet Army were distinct from those operated by the Soviet Air Defence Forces, which operated the bulk of the Soviet Union’s primarily fixed and semi-mobile medium- and long-range surface-to-air missile systems including the then-new S-300 as well as the bulk of the acquisition radars that formed the core of the Soviet Union’s early warning radar network. 

The PLAAF does not operate in the Central European military-geographical context of the 1980s. As explained earlier, the primary limitations of the YJ-91 anti-radiation missile for the PLAAF are its large size and weight, which limits the number of anti-radiation missiles that can be carried by a given PLAAF aircraft as well as the range and payload of said aircraft, and its limited reported maximum range of 110 km. The reported nominal maximum range of 110 km places PLAAF aircraft launching a YJ-91 anti-radiation missile from a medium or high altitude within range of the American Patriot and the Taiwanese Tien Kung III (TK-3) long-range surface-to-air missile systems. 

While the PLAAF does not encounter a major threat from truly mobile short- and medium-range self-propelled surface-to-air missile systems in the Western Pacific – the United States, Japan, and Taiwan never emulated the Soviet Army’s approach to highly mobile wheeled let alone tracked self-propelled surface-to-air missile systems – the PLA as a whole does nevertheless face a situation in which it is likely to successfully employ ground-launched ballistic missiles and/or air-launched munitions to target Taiwan’s stationary and semi-mobile acquisition radars and emplaced – temporarily stationary – surface-to-air missile systems only to afterwards confront irregularly emitting Taiwanese air defences operating in a state of being. As a result of what is – in this report’s view – likely to be a successful but inconclusive “first” salvo, the PLA as a collective will likely have to suppress – and ideally destroy – surviving air defence systems in Taiwan if the bulk of the air-launched strike capabilities resident in the PLAAF – and to a far lesser degree in the PLANAF and PLAGF rotary aviation – are to be brought to bear. 

The PLAAF of early 2025 does not appear to be equipped or trained for sustained operations aimed at suppressing or destroying intermittently emitting air defences operating in a state of being. There is, as such, a strong possibility that the PLAAF will be unable to bring to bear the bulk of its air-launched strike capabilities over much of the island of Taiwan, let alone the more distant Ryukyu Islands or even more distant potential targets elsewhere in Japan or across the Philippine archipelago. Given this dynamic, the PLAAF is likely to pursue a standoff loitering anti-radiation missile and may have already done so. Before examining the candidate Chinese design, the KF-088C, it bears emphasis that Taiwan and Japan’s Ryukyu Islands amount to much more compact geographies than the combined surface area of East Germany and the adjacent areas in West Germany and Poland. The range and endurance requirements that the PLAAF encounters are therefore very different, and the late Cold War British ALARM and American AGM-136 Tacit Rainbow designs are therefore likely to amount to imperfect templates for the PLAAF to emulate.

KF-088C Loitering Anti-Radiation Missile

Although there is no public indication that China has developed a clean sheet analogue to the American AGM-136 Tacit Rainbow air-launched loitering anti-radiation missile, there are indications that the PLAAF operates a version or derivative of an existing design that is intended to function as a loitering passive radiation homing anti-radiation missile. Formally unveiled with little fanfare at the 2022 Zhuhai Airshow, where it was loaded onto operational PLAAF JH-7A and J-16 aircraft on static display, the KF-088C appears to be an evolution of the turbojet-powered KD-88 air-launched cruise missile family with a substantially revised airframe. The KF-088C dispenses with the characteristic mid-section cruciform wings of the KD-88 design family, which contain data link antennas, and instead incorporates ventral folding wings with the likely effect of substantially improved glide performance. With the KD-88 family of air-launched cruise missiles being closely related to the YJ-83 family of anti-ship cruise missiles, the KF-088C may be compared to the American AGM-84H/K SLAM-ER, which succeeded the AGM-84E SLAM, an air-launched human-in-the-loop land-attack cruise missile derivative of the AGM-84 Harpoon family of anti-ship cruise missiles.

The PLAAF JH-7A and J-16 aircraft on static display at the 2022 Zhuhai Airshow were notably equipped with both the KF-088C and the new KF-98 air-launched cruise missile. The PLAAF did not, however, disclose the specifications of these previously unseen air-launched munitions and instead hosted what is best characterized as a “show, don’t tell” static display with these aircraft. Although the exact function of the KF-088C is subject to considerable uncertainty, there are indications that the KF-088C amounts to a passive radiation homing loitering anti-radiation missile (i.e., a loitering cruise missile equipped with a passive radiation homing seeker). It is, however, possible that the KF-088C airframe also exists in one or more other variants that amount to an extended range derivative of the KD-88 air-launched cruise missile family that is comparable to the American AGM-84H/K SLAM-ER. The KF-088C appears to be related to, if not the same as, a loitering anti-radiation missile offered to international customers with the export designation TL-30.

Notwithstanding differences in the appearance of the TL-30 mockups displayed at military industrial exhibitions – which are not functioning live rounds – the specifications of the TL-30 are likely to approximate that of the KF-088C. That said, China formally restricts the range of exportable missile designs to 300 km, which is the limit established in the Missile Technology Control Regime (MTCR) of which China is not a formal member. Specifications disclosed at military industrial exhibitions indicate that the exportable TL-30 has a maximum range of 280 km while equipped with a payload of unknown weight. The large air inlet under the KF-088C and TL-30 airframes are indicative of air-breathing propulsion, which is to say the use of a turbojet or perhaps a turbofan engine. 

When launched from a PLAAF aircraft at a medium or high altitude and at a high subsonic speed, the combination of an air-breathing engine and the ventral folding wings – as well as what may be a substantial reduction in the weight of the warhead – are likely to result in a considerable increase over the reported 200 km nominal maximum range of the KD-88 air-launched cruise missile. The maximum practical range of the KF-088C is affected by its flight profile. All else being equal, range can be maximized with a higher-altitude flight profile that minimizes the time-distance spent at lower altitudes. As with any air-launched munition, the maximum practical range of the KF-088C is affected by the speed and altitude of the host aircraft at the time the munition separates from the host aircraft.

All else being equal, an air-breathing subsonic anti-radiation missile will be much smaller and lighter than a supersonic solid-fuelled rocket-powered missile of comparable range and payload. At the cost of a longer time-to-target, an air-breathing subsonic anti-radiation missile can loiter over an area until the onboard passive radiation homing seeker detects a suitable target. There are, however, limits to the duration of loitering possible with a turbojet- or turbofan-powered subsonic missile. All else being equal, speed comes at the cost of range-endurance even in a missile equipped with an air-breathing engine that draws oxidizer from the atmosphere. Assuming a lower cruise speed of around 800 km/h, a 300 km range subsonic loitering anti-radiation missile will have a maximum flight time of around 22.5 minutes. Supposing that it is launched at a standoff range of 200 km, said missile will have around 7.5 minutes of loiter time once it reaches the target area located 200 km away. Depending on how much Chinese designers have substituted payload for range relative to the original reportedly 165 kg warhead used installed in the KD-88 air-launched cruise missile, it is possible that the KF-088C carries 80 or more kilograms of additional jet fuel and may as such have a substantially longer maximum loiter time when launched at a given standoff distance. The decades-old turbojet-powered Israeli Delilah air-launched loitering missile serves to illustrate the maximum range-endurance possible when a missile is equipped with a very small warhead of no more than several dozen kilograms.

Uncertainties notwithstanding, a KF-088C/TL-30 loitering anti-radiation missile offers the PLAAF a substantially different – and complementary – suppression of air defence capability than the YJ-91 and other supersonic anti-radiation missile designs. Although the PLAAF is likely to develop a long-range supersonic anti-radiation missile with a short time-to-target comparable to the American AGM-88G AARGM-ER if it has not done so already, there is a case to be made that a loitering anti-radiation missile in the vein of the KF-088C/TL-30 will be key to suppressing if not destroying Taiwanese surface-to-air missile systems and acquisition radars once these displace in the aftermath of what is likely to be successful but inconclusive initial PLA salvo targeting Taiwan’s stationary and emplaced air defence systems. As a result, the KF-088C/TL-30 loitering anti-radiation missile may be key to bringing the bulk of the PLAAF’s strike capabilities to bear against Taiwan. That said, it bears emphasis that the KF-088C, which is not a clean sheet design, reflects minimal effort toward reducing the radar signature of the airframe and the KF-088C, therefore, amounts to a step back for the PLAAF when compared to the KF-98 air-launched cruise missile alongside which the KF-088C was formally unveiled in 2022. While this may simply reflect the fact that the KF-088C was developed some years before it was formally unveiled, it may also indicate the PLAAF is unwilling and/or unable to allocate the resources required to deploy a sufficiently large number of a notional loitering anti-radiation missiles designed with a low radar signature. 

The KF-088C air-launched loitering subsonic anti-radiation missile can be employed by 22.75% of the combined fleet of ~2200 non-bomber crewed fixed-wing combat aircraft reportedly deployed by the PLAAF and PLANAF as of early 2025. The integration of the KF-088C has been confirmed with the JH-7A (x4) and the J-16 (x4).