Query: What year did the Korean War start?
Context: During the Cold War, American troops and their allies fought Communist forces in Korea and Vietnam. The Korean War began in 1950, when the Soviets walked out of a U.N. Security meeting, removing their possible veto. Under a United Nations umbrella, hundreds of thousands of U.S. troops fought to prevent the takeover of South Korea by North Korea, and later, to invade the northern nation.