While President Trump can decide whether to use force against Iran, Congress has taken steps that may make him unwilling to do so.
Throughout history, presidents and congresses have jockeyed for control over war powers. Article I of the Constitution grants Congress the exclusive authority to declare war, while Article II names the President as “Commander in Chief” of the army, navy and militia. The jockeying reached a watershed moment of congressional assertiveness with the passage of the 1973 War Powers Act. Since then, however, presidential war-making power has been in a state of near-constant expansion—an expansion only accelerated by overseas counterterrorism actions and recent presidential military actions in Libya and Syria.