Kh-31: Russia's supersonic anti-radar and anti-ship missile

The Kh-31 (Russian Х-31), known to NATO as the AS-17 Krypton, is a Russian-made air-to-surface missile, first developed in the Soviet Union, built in two main forms: the Kh-31P, which homes on the emissions of enemy radars, and the anti-ship Kh-31A. TWZ describes it as a ramjet-powered weapon¹ sold in both versions. It was designed by the Zvezda bureau, which was absorbed into the Tactical Missiles Corporation in 2002². Russia fires the Kh-31P at Ukraine, where the Air Force reports it by name in its night summaries: in the night to 26 October 2026³ it counted one Kh-31P anti-radiation missile⁴ among the weapons launched.

Design and development

Work on the family began in the late 1970s. The original requirement was a fast anti-radiation missile against the radars of new Western air defences such as the Patriot and the US Navy’s Aegis¹. Zvezda, which had built the Kh-25 family, started work on a long-range one, and the first launch took place in 1982. The anti-radar Kh-31P entered service in 1988 and the anti-ship Kh-31A in 1989⁵. The two versions were first shown in public in 1991, the Kh-31P at Dubai and the Kh-31A at Minsk².

The missile has been described as a miniaturised version of the P-270 Moskit ship-launched missile, with cruciform titanium wings and control surfaces. A solid-fuel booster in the tail fires first; once it burns out, its empty case serves as the combustion chamber of a kerosene ramjet fed by four air intakes. TWZ gives the booster’s work as accelerating the missile to Mach 1.8¹, after which the ramjet reaches Mach 3.5 at 53,000 ft, or Mach 1.8 at sea level. The anti-radar seeker of the Kh-31P uses an array of seven spiral antennas² on a steerable platform.

Specifications

The first-generation Kh-31A is 15 ft 5 in (4.7 m) long¹, and the missiles are 36 cm in diameter. The Kh-31P weighs 600 kg at launch and carries an 87 kg warhead, while the Kh-31A weighs 610 kg with a 94 kg penetrating warhead. The Kh-31P has a range of up to 110 km, which Militarnyi also gives⁵, and both versions have a top speed of 2,160 to 2,520 km/h².

TWZ gives the anti-ship Kh-31A a range of 9.3 to 31 miles¹ (15 to 50 km). The second-generation Kh-31AD and Kh-31PD were lengthened from 4.70 m to 5.3 m² to increase their range.

Launch platforms

The Kh-31 can be fitted to almost any Russian tactical aircraft², from the Su-17 to the MiG-31. Listed carriers of both versions include the Su-24M, Su-34 and Su-35, which Militarnyi also names⁵, as well as the Su-25, the Su-27SM, the Su-30MKI, the MiG-29M and MiG-29K and India’s HAL Tejas, while the Su-33 carries only the Kh-31A. The US Navy launched its MA-31 targets from the F-4 Phantom.

In late January 2026, according to a Telegram channel cited by Militarnyi, Spanish fighters on NATO’s Baltic air policing mission intercepted a Russian Su-30SM2 carrying two Kh-31A missiles and two RBK-500 cluster bombs⁶.

Operators and combat use

TWZ counts around a dozen operators outside Russia, among them China, India and Vietnam. India bought Kh-31s for its Su-30MKI in 2001 and appears to have bought 60 Kh-31A and 90 Kh-31P², and listed deliveries include 125 missiles to Algeria in 2007 to 2009 and 222 to Russia in 2009 to 2010. Venezuela received 24 Su-30MK2V fighters between 2006 and 2008; TWZ wrote in October 2025 that the Kh-31A, at least, appears to have been supplied with them, while delivery of the Kh-31P was unclear. In 2025 footage showed Serbian MiG-29s with Kh-31 missiles⁷ at Batajnica air base, Militarnyi reported, although Serbia had announced no such programme. The United States bought Kh-31s to turn them into anti-ship missile targets¹ for testing its warships’ defences.

Some reports say a Russian Su-34 used Kh-31Ps against a Georgian air defense radar near Gori on 10 August 2008. In Ukraine, Militarnyi reported on 9 March 2022 that Ukrainian air defense had shot down a Kh-31P near Berdychiv⁸ in Zhytomyr region. Russia has used the Kh-31 in its invasion of Ukraine², and senior Ukrainian Air Force sources said Kh-31P and Kh-58 missiles had destroyed some Osa and Buk air defence systems. In August 2024 Ukraine’s commander-in-chief Oleksandr Syrskyi grouped it with other air-launched missiles: of 1,547 Kh-25, Kh-29, Kh-31, Kh-35, Kh-58, Kh-59 and Kh-60 missiles⁹ launched since February 2022, he said, 343 had been shot down. In the night to 15 May 2026 the Air Force reported five Kh-31P missiles¹⁰ fired from the airspace over the Black Sea, none of which reached its target, and in the night to 26 October 2026 one Kh-31P³ alongside three Kh-59/69 missiles.

Variants

• Kh-31P: the anti-radiation version, offered with three seekers² for different sets of radars.
• Kh-31A: the anti-ship version with an active radar seeker, for ships of up to 4,500 tonnes².
• Kh-31PK: an anti-radar missile with a proximity fuze and a range of 120 to 160 km, in serial production since 2009².
• Kh-31AD, Kh-31PD and Kh-31PM: the second generation⁵; the lengthened Kh-31PD was in serial production by 2012² and the Kh-31AD from 2013, while the Kh-31PM is a modernised Kh-31P with a longer range and a new multi-band seeker.
• MA-31: a US Navy target drone conversion, tested between 1996 and 2007².
• KR-1 and YJ-91: the Kh-31P version sold to China and its Chinese-built derivative².

Similar weapons

• Kh-35: Zvezda’s subsonic turbojet anti-ship missile¹¹, designed against vessels of up to 5,000 tonnes¹², where the Kh-31 family uses a rocket-ramjet for sustained supersonic speeds¹.
• Kh-58: Raduga’s earlier anti-radiation missile, in service from 1978² with similar speed and range to the Kh-28 it replaced.
• AGM-88 HARM: an anti-radiation missile that the US supplied to Ukraine in 2022 and that has been fired from upgraded Ukrainian MiG-29s¹³.