In the EC-121 shootdown incident of 15 April 1969, an EC-121M of the U.S. Navy's Fleet Airborne Reconnaissance Squadron One (VQ-1) Vietnam, took off on a routine SIGINT patrol under the BEGGAR SHADOW program. North Korean air search radar was monitored by the USAF 6918th Security Squadron in Japan, and Detachment 1 6922nd Security Wing at Osan Air Base in Korea, and the Naval Security Group at Kamiseya, Japan. The EC-121M was not escorted. When US radar detected the takeoff of North Korean interceptors, and the ASA unit lost touch, ASA called for fighters, but the EC-121M never again appeared on radar. 31 crewmen were lost.