Russian Air Force is testing a new advanced tactical air-to-air missile 2501121.

The missile will be carried by MiG-31BM Foxhound supersonic interceptors/fighters and will subsequently be used by other warplanes, he said.

The weapon is “currently in trial at an Air Force test site,” Zelin said.

Zelin did not identify the missile but experts believe it could be the K-37M, also known as RVV-BD, or AA-X-13 Arrow as it is known to NATO.

The K-37M is a long-range air-to-air missile developed specifically for the MiG-31BM interceptor.

“A likely candidate is the Vympel (now part of TRV) K-37M long-range air-to-air missile. This is a successor to the R-33 (Nato codename AA-9 Amos) which was developed originally for the MiG-31 during the early 1970s,” said Douglas Barrie, an air warfare expert at the London-based International Institute for Strategic Studies.

Work on the K-37 program began during the 1980s, but funding problems delayed its completion, he added. The design has also been further developed since its original conception.

The K-prefix denotes a weapon in development while the M indicates a modification. An export variant of the weapon, known as RVV-BD, was shown at MAKS 2011. The BD suffix may stand for the Russian words bolshoi dalnost, or long range.

“The K-37M - it will likely be known as the R-37M when it enters service - will be the primary air-to-air armament of the MiG-31BM, providing the Russian air force with an extended range interception capability against combat aircraft and cruise missiles,”