US President Donald Trump has ordered Marines into Los Angeles, vowing that protesters against immigration arrests will be "hit harder" than ever, AFP reports.

The extraordinary mobilization of 700 full-time professional troops - who join hundreds of National Guard troops - looked set to further inflame tensions in the city with a huge Latino population.

California Governor Gavin Newsom denounced the move as "insane."

"U.S. Marines have served with honor in numerous wars in defense of democracy," Newsom wrote in X.

"They should not be deployed on American soil, facing their own countrymen, to fulfill the insane fantasy of a dictatorial president. That is un-American," he added.

The order came after demonstrators took over the streets of downtown Los Angeles on June 8, setting fire to cars and looting stores, to which law enforcement responded with tear gas and rubber bullets.

"The people who are creating the problems are professional agitators and rioters," Trump said.

On social media, he said he sent National Guard troops "to deal with the violent, unprovoked riots" and "if we hadn't, Los Angeles would have been completely destroyed."

He said the protesters were spitting on the soldiers and if they continued to do so, "I promise you they will be hit harder than they have ever been hit before. Such disrespect will not be tolerated!" | BGNES