California Governor Gavin Newsom took to the airwaves Tuesday night — with federal troops stationed in his state’s largest city and immigration agents rounding up residents — and warned Americans that democracy itself was under attack from President Donald Trump.

The Insurrection Act is a federal law that allows the president to deploy the military and National Guard troops to suppress civil disorder, insurrection or rebellion. It was last used by President George H. W. Bush during the Los Angeles riots after the Rodney King verdict in April 1992.