1950 – The United States decides to send troops to fight in the Korean War. The Korean War (25 June 1950 – 27 July 1953) was an armed conflict fought on the Korean Peninsula between North Korea (Democratic People's Republic of Korea; DPRK) and South Korea (Republic of Korea; ROK) and their allies. North Korea was supported by China and the Soviet Union, while South Korea was supported by the United Nations led by the United States under the auspices of the United Nations Command (UNC). After the end of World War II in 1945, Korea, which had been a Japanese colony for 35 years, was divided by the Soviet Union and the United States into two occupation zones at the 38th parallel, with plans for a future independent state. Due to political disagreements the zones formed their own governments in 1948. North Korea was led by Kim Il Sung in Pyongyang, and South Korea by Syngman Rhee in Seoul; both claimed to be the sole legitimate government of all of Korea. On 25 June 1950, the North Korea's Korean People's Army (KPA) launched an invasion of the south. In the absence of the Soviet Union's representative, the UN Security Council denounced the attack and called on member nations to provide military assistance to repel the invasion. UN forces under the unified command comprised 21 countries, with the US providing around 90% of military personnel. On 27 June 1950 President Harry S. Truman ordered US air and sea forces to aid South Korea. Combat ended on 27 July 1953 with the signing of the Korean Armistice Agreement, which allowed the exchange of prisoners and created a 4-kilometre wide (2.5 mile) Demilitarized Zone (DMZ) along the frontline, with a Joint Security Area at Panmunjom. The industrial warfare was defined by armored offensives, with the North's initial invasion and later by UN forces, tunnel warfare by Chinese forces, and the first large jet aircraft battles. North Korea became one of the most heavily bombed countries in history. The conflict caused around one million military deaths and an estimated 1.5 million to 3 million civilian deaths. No peace treaty has been signed; the Korean conflict remains a frozen conflict, which has occasionally flared, such as in the 1966–1969 DMZ Conflict.