The Korean conflict is based on the division between the Democratic People's Republic of Korea in the north and the Republic of Korea in the south, both of which claim to be the government of the entire peninsula. During the Cold War, North Korea was backed by the Soviet Union, China and other communist states, and South Korea was backed by the United States and its allies. The division of Korea occurred at the end of World War II in 1945, and tensions erupted into the Korean War in 1950. When the war ended, the country was devastated, but the division remained. North and South Korea continued a military standoff, with periodic clashes. The conflict survived the collapse of the Eastern Bloc of 1989 to 1991.
The U.S. maintains a military presence in the South to assist South Korea in accordance with the ROK–US Mutual Defense Treaty. In 1997, U.S. President Bill Clinton described the division of Korea as the "Cold War's last divide". In 2002, U.S. President George W. Bush described North Korea as a member of an "axis of evil". Facing increasing isolation, North Korea developed missile and nuclear capabilities.