The Asama-Sansō incident was a hostage crisis and police siege at a mountain lodge near Karuizawa in Nagano Prefecture, Japan, which lasted from February 19 to February 28, 1972. The police rescue operation on the final day of the standoff was the first marathon live television broadcast in Japan, lasting 10 hours and 40 minutes.

The United Red Army was a militant organization that operated in Japan between July 1971 and March 1972. The URA was formed as the result of a merger that began on 13 July 1971 between two extremist groups, the Marxist–Leninist–Maoist Red Army Faction , led in 1971 by Tsuneo Mori, and the Reformed Marxist Revolutionary Left Wing group, Japanese Communist Party Kanagawa Prefecture Committee, also known as the Keihin Anti-Security Treaty Joint Struggle Group , led by Hiroko Nagata.