When the Soviet Union agreed to join forces against Japan, on 8 August, the USSR also became a party to the Cairo Declaration. According to terms of the Japanese capitulation on 11 August, the Soviets were to accept surrender of the defeated forces north of the 38th Parallel in Korea. South of that line, the commander of the American occupation forces would receive the surrender. The Russians wasted no time and on 12 August had their troops in northern Korea. American combat units, deployed throughout the Pacific, did not enter Korea until 8 September. Then they found the Soviet soldiers so firmly established they even refused to permit U.S. occupation officials from the south to cross over into the Russian sector. A December conference in Moscow led to a Russo-American commission to work out the postwar problems of Korean independence. Meeting for the first time in March 1946, the commission was short-lived. Its failure, due to lack of Russian cooperation, paved the way for politico-military factions within the country that set up two separate Koreas. In the north the Communists, under Kim Il Sung, and in the south the Korean nationalists, led by Dr. Syngman Rhee, organized independent governments early in 1947. In May of that year, a second joint commission failed to unify the country. As a result the Korean problem was presented to the United Nations (UN). This postwar international agency was no more successful in resolving the differences between the disputing factions. It did, however, recognize the Rhee government in December 1948 as the representative one of the two dissident groups. In June 1950, the North Koreans attempted to force unification of Korea under Communist control by crossing the 38th Parallel with seven infantry divisions heavily supported by artillery and tanks. Acting on a resolution presented by the United States, the United Nations responded by declaring the North Korean action a “breach of the peace” and called upon its members to assist the South Koreans in ousting the invaders. Many free countries around the globe offered their aid. In the United States, President Harry S. Truman authorized the use of U.S. air and naval units and, shortly thereafter, ground forces to evict the aggressors and restore the status quo. Under the command of General of the Army Douglas MacArthur, then Far East Commander, U.S. Eighth Army occupation troops in Japan embarked to South Korea.