cancelled Duck Hook, it seems that Nixon embarked on a new strategy to start a "series of increased [nuclear] alert measures designed to convey to the Soviets an increasing readiness by U.S. strategic forces," according to Kissinger aide Alexander Haig . Further reading Burr, William. (2015). Nixon's Nuclear Specter The Secret Alert of 1969, Madman Diplomacy, and the Vietnam War. University Press of Kansas. Nina Tannenwald (2006) "Nuclear Weapons and the Vietnam War." Journal of Strategic Studies, 29:4, 675-722 References United States intelligence operations