U.S. President Donald Trump walks with Chief of Naval Operations Admiral Daryl Caudle, aboard the aircraft carrier USS George H.W. Bush off the coast of Norfolk, Virginia, U.S. October 5, 2025. REUTERS/Jonathan Ernst REFILE - CORRECTING FROM "U.S. ARMY" TO "CHIEF OF NAVAL OPERATIONS ADMIRAL DARYL CAUDLE".

(Reuters) -Donald Trump's threat to invoke a federal anti-insurrection law to expand his deployment of military personnel to U.S. cities has intensified the legal battle between the president and Democratic-led cities, as hundreds of National Guard troops from Texas on Tuesday prepared to patrol the streets of Chicago.

Trump told reporters on Monday that he would consider utilizing the Insurrection Act, a law enacted more than two centuries ago, to sidestep any court rulings restricting his orders to send Guard troops into cities over the objections of local and state officials.

"We have an Insurrection Act for a reason," Trump said. "If people were being killed and courts were holding us up, or governors or mayors were holding us up, sure, I'd do that."

The law, which gives the president authority to deploy the military to quell unrest in an emergency, has typically been used only in extreme cases, and almost always at the invitation of state governors. The act was last invoked by President George H.W. Bush during the Los Angeles riots of 1992.

Using the act would represent a significant escalation of Trump's campaign to deploy the military to the streets of Democratic cities in an extraordinary assertion of presidential power. Last week, in a speech to top military commanders, Trump suggested using U.S. cities as "training grounds" for the armed forces.

Trump has ordered Guard troops sent to Chicago, the third-largest U.S. city, and Portland, Oregon, following his earlier deployments to Los Angeles and Washington, D.C. In each case, he has done so despite staunch opposition from Democratic mayors and governors, who say Trump's claims of lawlessness and violence do not reflect reality.

In Chicago and Portland, protests over Trump's immigration policies had been largely peaceful, while both cities have seen sharp declines in violent crime so far this year, according to local officials. Clashes between protesters and federal agents, who have fired tear gas and other crowd deterrents, increased over the weekend as tensions grew over Trump's determination to send in Guard troops.

Illinois Governor J.B. Pritzker, a Democrat, accused Trump of intentionally trying to foment violence in Chicago by sending in immigration agents and Guard troops, which the president could then use to justify further militarization.

"Donald Trump is using our service members as political props and as pawns in his illegal effort to militarize our nation's cities," Pritzker told reporters on Monday.

Illinois and Chicago sued the Trump administration on Monday, seeking to block orders to federalize 300 Illinois Guard troops and send 400 Texas Guard troops to Chicago. During a court hearing, Justice Department lawyers told a federal judge that hundreds of Texas Guard troops were already in transit to Illinois.

The judge, April Perry, permitted the deployment to proceed for now but ordered the U.S. government to file a response by Wednesday.

Separately, a federal judge in Oregon on Sunday temporarily blocked the administration from sending any National Guard troops to police Portland, the state's largest city.

National Guard troops are state-based militia who normally answer to the governors of their states and are often deployed in response to natural disasters. A federal law, the Posse Comitus Act, generally bars the military from domestic law enforcement, but the Insurrection Act operates as an exception to that law.

(Reporting by Emily Schmall in Chicago and Nate Raymond and Dietrich Knauth in New York; Additional reporting by Brad Brooks; Writing by Joseph Ax; Editing by Frank McGurty and Nick Zieminski)