A recently released report indicates that the U.S. government prepared to declare a state of emergency and was ready to repel a North Korean assault following the South Korean military's coup d'état on Dec. 12, 1979.

Titled "North Korean Reaction to Instability in the South," the report was written by the U.S. Central Intelligence Agency (CIA) about a week after the December coup. It projected a 50:50 chance of large-scale military action by the communist North and added that the main deterrent preventing Pyongyang from taking action was the presence of U.S. forces in the South.

Other intelligence organizations including the U.S. State Department, the Defense Intelligence Agency and the National Security Agency also contributed to the report.