evidence: By early August 1950, the North Korean army had overrun most of South Korea except for a small pocket in the far southeast known as the Pusan Perimeter. [...] The following month saw U.N. forces crossing the 38th parallel into North Korea, capturing Pyongyang, the capital of North Korea, and advancing to the Yalu River, the northern boundary of North Korea and China. [...] No peace treaty was ever signed between North and South Korea and in the decades since the Korean War, North Korean forces have conducted numerous cross-border incursions and other acts of aggression.