Which aircraft caused the largest loss of American crew members in a single Cold War shoot-down?

On 15 April 1969, a US Navy EC-121M Warning Star, belonging to reconnaissance squadron VQ-1 and with the radio call sign "Deep Sea 129," was shot down by two North Korean MiG-21s. The aircraft was flying over the Sea of Japan, about 90 nautical miles off the North Korean coast. All 31 Americans aboard died: 30 sailors and one marine. It is the largest loss of American crew members in a single incident of the entire Cold War.

The EC-121 was the radar surveillance version of the Constellation family, used by the US Navy and Air Force as an early warning and control aircraft. It was designed to complement the DEW (Distant Early Warning) line of ground-based radars and carried two large radomes, one vertical above the fuselage and one horizontal beneath it. Besides monitoring airspace, EC-121s were also used for signals intelligence gathering, the mission Deep Sea 129 was carrying out that day.

The attack caught the Nixon administration by surprise, which according to testimonies saw it as something entirely unexpected. Despite the scale of the loss, the United States did not retaliate beyond a brief naval show of force in the Sea of Japan, and within less than a week resumed reconnaissance flights in the area. The episode stands as one of the tensest moments between the two countries after the Korean War and as a reminder of the risk faced by intelligence crews, who flew unarmed near hostile territory for hours to monitor the adversary's transmissions.