This is the first supersonic anti-ship missile to arm tactical aircraft. Comparable to the ANS missile developed jointly by France and Germany, "Krypton" employs a solid fuel booster for initial thrust. Once at speed, the ramjets take over. One version has four individual ramjets spaced evenly around the outside of the airframe. This version, the Kh-31A, ducts the ramjet intakes into an internal combustion chamber. "Krypton" is an air-to-surface missile, carried by both Su-17M4s and Su-24Ms. However, an air-to-air, anti-radar version, designed for use against AWACS and similar aircraft, is also being developed.