According to the Republic of Korea's Yonhap news agency, the US Air Force WC-135 nuclear sniffer was flown to the Korean Peninsula on 20 April for an “emergency sortie” amid the possibility of North Korea's sixth nuclear test.
Derived from the Boeing C-135, WC-135 Constant Phoenix is a special-purpose aircraft to collect samples from the atmosphere in order to detect and identify a nuclear explosion.
211216-N-QI061-1222 NAVAL STATION MAYPORT, Fla. (December 16, 2021) An MQ-4C Triton Unmanned Aircraft System (UAS), assigned to Unmanned Patrol Squadron 19 (VUP-19), sits on the flight line at Naval Station Mayport, Florida, Dec. 16, 2021. VUP-19, the Navy’s first Triton squadron, will continue to maintain and operate the aircraft off the East Coast to further develop the concept of operations and refine tactics, techniques, and procedures. (U.S. Navy photo by Mass Communication Specialist 2nd Class Nathan T. Beard/ Released)