US Vice President JD Vance has said that the thousands of troops deployed to Los Angeles this month were still needed despite a week of relative calm in the protest-hit city.

US President Donald Trump has sent roughly 4,000 National Guard members and 700 Marines, purportedly to protect federal property and personnel, after demonstrations over immigration raids.

"Unfortunately, the soldiers and Marines are still very much a necessary part of what's going on here because they're worried that it's going to flare back up," Vance told reporters in Los Angeles.

He was speaking the day after an appeals court ruled that Trump could continue to control the California National Guard, which would normally fall under Governor Gavin Newsom's authority.

California officials have heavily criticised Trump over his use of the military, saying it escalated protests that local law enforcement could have handled.

The demonstrations were largely peaceful and mostly contained to a small part of Los Angeles, the second-largest US city, although there were instances of violence and vandalism.

"If you let violent rioters burn great American cities to the ground, then, of course, we're going to send federal law enforcement in to protect the people the president was elected to protect," Vance said, adding that Trump would deploy them again if needed.

The Republican further accused Newsom – a possible contender for the Democratic presidential nomination in 2028 – and Los Angeles Mayor Karen Bass of encouraging protesters.

Newsom and Bass have both condemned rioting and violence towards law enforcement while accusing the Trump administration of manufacturing a crisis in the city. (AFP)