In early September 2025, President Donald Trump announced that he would deploy federal troops into several major U.S. cities to quell unrest — even if governors objected.

The announcement immediately set off a wave of debate. Critics pointed to the Posse Comitatus Act of 1878, a law meant to prevent the use of the Army as a domestic police force. Supporters countered with the Insurrection Act of 1807, a much older law that presidents have invoked many times to justify troop deployments at home.

So here’s the central question for us today: Is Trump doing something unprecedented — or is he following a long, if uneasy, American tradition of presidents sending troops into the streets?