This report, issued in 1967 by the Institute for Defense Analyses, was formerly secret but was obtained under the Freedom of Information Act (FOIA) by the Nautilus Institute Nuclear Policy Project. The purpose of this study was to evaluate the military consequences of a U.S. decision to use tactical nuclear weapons (TNW) in Southeast Asia, under the assumption that the Vietnam War remained theater-limited and that no strategic exchange occurs. The study divides into two main parts: (1) possible targets for U.S. TNW, and the effects of nuclear bombardment on the ground war if the use of TNW remains unilateral; and (2) the possibility and effectiveness of enemy retaliation with nuclear weapons supplied by the USSR or China.