The 9K34 Strela-3 (Russian: 9К34 «Стрела-3»; English: arrow) man-portable air defence missile system (MANPADS) was developed in the Soviet Union as a response to the poor performance of the earlier 9K32 Strela 2 (SA-7 Grail) system. "9K34" is its GRAU designation and its NATO reporting name is SA-14 Gremlin. The missile was largely based on the earlier Strela 2, and thus development proceeded rapidly. The new weapon was accepted to service in the Soviet Army in January 1974.
The most significant change over the Strela 2 was the introduction of an all-new infra-red homing seeker head. The new seeker worked on FM modulation (con-scan) principle, which is less vulnerable to jamming and decoy flares than the earlier AM (spin-scan) seekers, which were easily fooled by flares and even the most primitive infrared jammers. Most importantly, the new seeker also introduced detector element cooling in the form of a pressurized nitrogen bottle attached to the launcher.
The effect of cooling was to expand the seeker's lead sulphide detector element's sensitivity range to longer wavelengths (slightly over 4 µm as opposed to 2.8 µm of uncooled PbS elements). In practice this made possible the tracking of cooler targets over longer ranges, and enabled forward-hemisphere engagement of jets under favourable circumstances.The seeker also had better tracking rate, enabling the missile to track maneuvering of fast and approaching targets.