"The United States is the power that introduced nuclear weapons into Korea, and it took this drastic step primarily to stabilize volatile North-South relations. Always suspicious of North Korea's intentions, in the mid-1950s the Eisenhower Administration also worried that South Korean President Syngman Rhee might reopen the war. Secretary of State John Foster Dulles wanted to restrain both sides -- with nuclear weapons. Even hotheads like Rhee and Kim Il Sung, he believed, would think twice before starting a war that would rain atomic destruction on the peninsula. In January of 1958 the United States positioned 280mm nuclear cannons and "Honest John" nuclear-tipped missiles in South Korea; these were followed a year later by nuclear-tipped Matador cruise missiles. Soon American and South Korean defense strategy rested on routine plans to use nuclear weapons very early in any new war -- at "H + 1," according to one former U.S. commander in Korea, meaning within one hour (more likely a few hours) of the outbreak of war if large masses of North Korean troops succeeded in attacking south of the DMZ. Annual "Team Spirit" military exercises included rehearsals for battlefield nuclear war. North Korea responded by building enormous facilities underground or in mountain redoubts, from troop and materiel depots to munitions factories and warplane hangars. This was a bit of a problem for American surveillance, in that it allowed for a great many places to hide an atomic bomb."