War power through restraint: The politics of unilateral military action after 1945

From a historical perspective, presidents have frequently directed the use of military force without explicit permission from Congress. Yet, presidents still court legislative approval on select occasions. Why do presidents sometimes seek congressional authorization and other times do not? I explain authorization‐seeking behavior according to variations in presidential bargaining strength. I argue that both weak and strong presidents prefer authorization‐seeking; by obtaining congressional backing, weak presidents conceal a lack of national resolve from international audiences, while strong ones use approval to enhance their coercive authority. Presidents with mid‐level bargaining strength, however, prefer unilateral action; on the one hand, unilateral action may demonstrate resolve in the face of potential legislative resistance, while on the other, it avoids contentious debate that risks “muddying” the diplomatic waters. I illustrate these arguments by revisiting four prominent historical cases: the Korean War, the Gulf of Tonkin crisis, the invasion of Cambodia, and the Persian Gulf War.