Modern airforces have become dependent on airborne radars typically carried by converted airliners and transport aircraft such as the E-3 Sentry and A-50 'Mainstay'. They also depend on similar aircraft for inflight refuelling (e.g. Vickers VC10), maritime patrol (e.g. CP-140 Aurora), reconnaissance and electronic warfare (e.g. Tu-16 'Badger' E & J) and C4ISTAR (e.g. VC-25 "Air Force One"). The loss of just one of these aircraft can have a significant effect on fighting capability, and they are usually heavily defended by fighter escorts. A long-range air-to-air missile offers the prospect of bringing down the target without having to fight a way through the fighter screen. Given the potential importance of "blinding" Western AWACS, Russia has devoted considerable resources to this area. The Vympel R-37 (AA-13 'Arrow') is an evolution of their R-33 (AA-9 'Amos') with a range of up to 400 km (220 nmi), and there have been persistent rumours – if little hard evidence – of an air-to-air missile with a range of 200 km (110 nmi) based on Zvezda's Kh-31 anti-radar/anti-shipping missile or its Chinese derivative, the YJ-91.
NPO Novator started work in 1991 on a very long-range air-to-air missile with the Russian project designation Izdeliye 172. Initially called the AAM-L (RVV-L), it made its first public appearance at the International Defence Exhibition in Abu Dhabi in early 1993, followed by the Moscow Air Show later that year. It was described as having a range of 400 km (220 nmi); the mockup on display had a strong resemblance to the 9K37M1 Buk-M (SA-11 'Gadfly'). Apparently some flight-testing was done on a Su-27, but it appears that the Russians withdrew funding for the project soon afterwards.
The missile resurfaced as the KS–172 in 1999, as part of a new export-led strategy whereby foreign investment in a 300 km (160 nmi)-range export model would ultimately fund a version for the Russian airforce. Again it appears that there were no takers.
In late 2003, the missile was offered again on the export market as the 172S-1. In March 2004, India was reported to have invested in the project and to be "negotiating a partnership" to develop the "R-172". In May 2005 the Indians were said to have finalised "an arrangement to fund final development and licence produce the weapon" in a joint venture similar to that which produced the successful BrahMos cruise missile. Since then the missile has had a higher profile, appearing at the 2005 Moscow Air Show on a Su-30 as the K-172, and a modified version being shown at the 2007 Moscow Air Show designated as the K-100-1. This name first appeared in a Sukhoi document in 2006, and sources such as Jane's now refer to the missile as the K-100.