Korean War two years of fighting became a war of attrition, with the front line close to the 38th parallel. The war in the air, however, was never a stalemate. North Korea was subject to a massive bombing campaign. Jet fighters confronted each other in air-to-air combat for the first time in history, and Soviet pilots covertly flew in defense of their communist allies. The fighting ended on 27 July 1953, when an armistice was signed. The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners. However, no peace treaty was ever signed,
Impact of the Korean War on the economy of the United States tensions with the Soviet Union, the Korean War further increased it. The Korean War cost the US$30 billion in 1953, which is equivalent to US$341 billion in 2011. During the last year of the war, annual war expenditure comprised about 14.1 percent of GDP. Approximately 34,000 Americans were killed in battle and about another 2,800 died from disease or injury, with total US casualties, which includes dead, wounded, and missing in action, adding up to 139,860. The "Korean War GI Bill" was implemented in 1952, eventually covering veterans between June 27, 1950 and February 1, 1955. It offered the same