The requesting unit would direct the air strikes. The U.S. Army would not copy the British system until the Allied invasion of Italy, but adapted it for use there and in France after the Invasion of Normandy of 6 June 1944. The United States would end World War II still without an air control doctrine. When the U.S. Air Force split from the U.S. Army in 1947, neither took on the responsibility for forward air control; the U.S. military thus had no functional forward air control when the Korean War broke out. The United Kingdom and Commonwealth continued to build on their experience in the Second World War in various campaigns around the world in the second half of the twentieth century, including the Malayan Emergency, the Suez Crisis, the Indonesian Confrontation and operations in Aden and Oman. With the re-formation of the Army Air Corps in 1957 this new corps's functions included airborne forward air control. Although the United States, as part of the United Nations Command (UNC) in the Korean War, entered the war on 26 June 1950 with no forward air controllers, it rapidly improvised close air support procedures for UNC forces. By 20 July, jury-rigged systems were not only controlling air strikes against the communist foe, but also occasionally directing aerial interceptions of opposing aircraft. Both the U.S. high command and North Korean General Nam Il agreed that only tactical air power saved United Nation forces from defeat during the mobile warfare stage of the war. When the front lines bogged down into static trench warfare in Summer 1951, forward air control diminished in importance. To cope with the communist switch to night operations, both radar and Shoran bombing techniques were developed. However, close air support continued, and sometimes used to direct interdiction missions against the communist lines of communications. By this time, Allied air forces were contributing a considerable portion of the tactical air strikes. By the cessation of hostilities, airborne forward air controllers alone were credited with flying 40,354 forward air control sorties, and directing air strikes that killed an estimated 184,808 communist troops. At times, tactical air was credited with inflicting about half of all communist casualties. Despite having agreed on a common forward air control doctrine as embodied in "Field Manual 31 - 35 Air-Ground Operations", a turf war over doctrine raged between the U.S. Air Force and the U.S. Army for the entire war. Additionally, the U.S. Marine Corps maintained its own FAC operation during the war. Also, U.S. Navy carrier aviation would not completely coordinate its operations with the Air Force/Army system until the final month of the war.