The US state of Oregon has filed a lawsuit challenging President Donald Trump’s move to send military forces into the Democratic-run city of Portland.

Trump on Saturday announced plans to send troops into the city, saying they would be used to protect federal immigration facilities against “domestic terrorists” and that he was authorising them to use “full force, if necessary”.

On Sunday, US Defence Secretary Pete Hegseth ordered 200 Oregon National Guard troops to be deployed under federal authority.

Trump’s deployments of military forces into other municipalities led by Democrats, including Los Angeles and Washington DC, have spurred similar legal challenges and protests.

Oregon’s suit was filed against Trump, Hegseth and US Homeland Security Secretary Kristi Noem in federal court in Portland on Sunday (local time) by Democratic Oregon Attorney-General Dan Rayfield. The suit accused Trump of exceeding his powers.

“Citing nothing more than baseless, wildly hyperbolic pretext – the President says Portland is a ‘War ravaged’ city ‘under siege’ from ‘domestic terrorists’. Defendants have thus infringed on Oregon’s sovereign power to manage its own law enforcement activity and National Guard resource,” the lawsuit said.

The state says protests against the US Immigration and Customs Enforcement agency in Portland have been small and relatively contained since June.

Trump’s planned deployment caught many at the Pentagon by surprise, six US officials told Reuters, speaking on condition of anonymity. On Sunday, Hegseth signed a memo ordering 200 Oregon National Guard troops deployed under federal authority. The memo was made public as an attachment to Oregon’s lawsuit.

The Pentagon did not immediately respond to a request for comment.

“Sending in 200 National Guard troops to guard a single building is not normal,” Rayfield said, apparently referring to an ICE facility.

Violent crime in Portland fell in the first six months of 2025, according to preliminary data released by the Major Cities Chiefs Association in its Midyear Violent Crime Report. Homicides fell by 51 per cent compared to the same period a year earlier, according to these statistics.

Since returning to the White House in January, Trump has made crime a major focus of his administration even as violent crime rates have fallen in many US cities.

In 2020, protests erupted in downtown Portland, the Pacific Northwest enclave with a reputation as a liberal city, following the killing in Minneapolis of George Floyd by a white police officer. The protests dragged on for months, and some civic leaders at the time said they were spurred rather than quelled by Trump’s deployment of federal troops.

It was unclear whether Trump’s warning that US troops could use “full force” on the streets of Portland meant he was somehow authorising lethal force and, if so, under what conditions. US troops are able to use force in self-defence on domestic US deployments.

Portland Mayor Keith Wilson, like other Oregon officials, learned of Trump’s order from social media on Saturday. He condemned the move outright.

“This is an American city,” Wilson said on Saturday.

“We do not need any intervention. This is not a military target.”

Many in Trump’s own Pentagon were also caught off guard.

“It was a bolt from the blue,” one of the US officials said, adding that the military was previously focused on carrying out prudent planning for potential deployments of troops by Trump into cities such as Chicago and Memphis.

Tensions have spiked in many big US cities over Trump’s aggressive immigration crackdown, days after a shooting targeting an Immigration and Customs Enforcement facility in Dallas left one detainee dead and two others seriously wounded.