Hundreds of Marines were due to arrive in Los Angeles on Tuesday after US President Donald Trump ordered their deployment in response to protests against immigration arrests and despite objections by state officials.
The 700 crack troops will join National Guard soldiers, amping up the militarization of the tense situation in the sprawling city, which is home to millions of foreign-born and Latino residents.
The largely peaceful demonstrations -- marred by sporadic but violent clashes between police and protesters -- were entering their fifth day. The unrest was sparked by a sudden intensification of Trump's signature campaign to deport illegal migrants, with raids conducted on workplaces.
In downtown LA's Little Tokyo neighborhood at night Monday, scores of protesters faced off with security officials in riot gear, some shooting fireworks at officers who fired back volleys of tear gas.
Earlier, demonstrators marching with banners and handmade signs yelled "ICE out of LA" and "National Guard go away" -- a reference to immigration agents and Guard soldiers.
California officials have stressed the majority of protesters have been peaceful and that they were capable of maintaining law and order themselves.
Democratic Governor Gavin Newsom wrote on X that US Marines "shouldn't be deployed on American soil facing their own countrymen to fulfill the deranged fantasy of a dictatorial President. This is un-American."
Trump, meanwhile, has branded the LA protesters "professional agitators and insurrectionists."
"If I didn't 'SEND IN THE TROOPS' to Los Angeles the last three nights, that once beautiful and great City would be burning to the ground right now," he wrote on Truth Social on Tuesday.
One small business owner in the city, whose property was graffitied during the protests, was supportive of Trump's strong-arm tactics.
"I think it's needed to stop the vandalism," she told AFP, declining to give her name.
Others were horrified.
"They're meant to be protecting us, but instead, they're like, being sent to attack us," Kelly Diemer, 47, told AFP. "This is not a democracy anymore."
Police have detained dozens of protesters in LA in the recent days, while authorities in San Francisco and other US cities have also made arrests.
- 'Incredibly rare' -
Trump's use of the military is an "incredibly rare" move for a US president, Rachel VanLandingham, a professor at Southwestern Law School in Los Angeles and a former lieutenant colonel in the US Air Force, told AFP.
The National Guard -- a fully equipped reserve armed forces -- is usually controlled by state governors and used typically on US soil in response to natural disasters.
The Guard has not been deployed by a president over the objections of a state governor since 1965, at the height of the civil rights movement.
Deployment of regular troops, such as the Marines, on US soil is even more unusual.
US law largely prevents the use of the military as a policing force -- absent an insurrection. Speculation is growing that Trump could invoke the Insurrection Act giving him a free hand to use regular troops for law enforcement around the country.
The Pentagon said late Monday that Trump had authorized an extra 2,000 state guardsmen to LA.
The state of California has sued to block the use of the Guard troops and Newsom said he would also sue against the Marines deployment.
