The AN/ALQ-144, AN/ALQ-147, and AN/ALQ-157 are US infra-red guided missile countermeasure devices (IRCM). They were developed by Sanders Associates in the 1970s to counter the threat of infra-red guided surface to air missiles like the 9K32 Strela-2. While decoy flares were effective at jamming first generation infra-red guided missiles, each flare was only effective for a short period. If an aircraft needed to loiter over a high risk area or was flying slowly (as helicopters do), it would require a large number of flares to decoy any missile fired at it. The IRCM provided constant protection against infra-red guided missiles.