Presidential Decision Directive 59 -- presented here on Foreign Policy's National Security channel and on the National Security Archive's website for the first time -- was one of the most controversial nuclear policy documents of the Cold War, yet until now it's never been made public in its entirety.

Signed by President Jimmy Carter on July 25, 1980, the directive (titled "Nuclear Weapons Employment Policy") aimed to give presidents more flexibility in planning for and executing a nuclear war -- that is, options beyond a massive strike. Leaks of the document's Top Secret contents, within weeks of its approval, gave rise to front-page stories in the New York Times and the Washington Post, alleging that its changes to U.S. strategy lowered the threshold of a decision to go nuclear.

With other recently declassified material, PD-59 shows that the United States was indeed preparing to fight a nuclear war, with the hope of enduring. To do this, it sought a nuclear force posture that ensured a "high degree of flexibility, enduring survivability, and adequate performance in the face of enemy actions." If deterrence failed, the United States "must be capable of fighting successfully so that the adversary would not achieve his war aims and would suffer costs that are unacceptable."...