Project Blue Book Case #1061. On February 23, 1952, an unidentified object was observed over Sinuiju, North Korea — a city on the Yalu River directly across from the Chinese border. Sinuiju sat at the very heart of "MiG Alley," the northwestern corner of Korea where American F-86 Sabres and Soviet-flown MiG-15s engaged in daily aerial combat — the first jet-versus-jet dogfights in history.
This was not just an unknown over friendly territory — it was an unknown over the most dangerous airspace on Earth, directly on the border with Communist China, where Soviet, Chinese, and American fighters were killing each other every day. Any unidentified object here could be a new enemy weapon, a Soviet experimental aircraft, or something that belonged to no nation's inventory.
The object did not match any known friendly, enemy, or Chinese aircraft. Far East Air Forces intelligence investigated through combat channels. The case was classified "Unknown" — from the only location in the Blue Book files where an unidentified object appeared over an active combat zone against enemy jet fighters.