Presidents may also use the armed forces to maintain “the peace of the United States,” as several presidents in the late nineteenth and early twentieth centuries did in enforcing district court injunctions against striking miners and railway workers. Domestically, this may mean using or threatening to use force to make sure that laws are faithfully executed, as George Washington did when he rode out at the head of a column of troops to put down the Whiskey Rebellion, as Andrew Jackson did in 1832 when he threatened to use force against South Carolina if it did not permit collection of the tariff, and as Abraham Lincoln did to end the secession of Southern states. May the president use force if he believed an attack were imminent use force without a declaration of war defend American lives and property abroad execute treaty obligations involving the armed forces or engage in “coercive diplomacy” to get leaders of other nations to accede to his wishes? The president's most important duty as commander in chief is to defend the United States, its territories and possessions and its armed forces, from attack. The Constitution (Article II, section 2) specifies that “The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several states, when called into the actual Service of the United States.” This language provides the president with constitutional powers over the armed forces, powers shared with Congress but the constitutional framework leaves several unsettling questions unanswered.

Commander in chief of military