LOS ANGELES, United States (AFP) — Protests against Donald Trump’s harsh immigration policies spread Wednesday across the United States (US) despite a military-backed crackdown in Los Angeles and a threat by the Republican president to use “heavy force.”

In Los Angeles, where the unrest began last Friday, an overnight curfew in the downtown area saw police make 25 arrests by morning.

Heavily armed officers patrolled near government buildings, and storekeepers boarded up windows to protect against vandalism.

US Marines — ordered by Trump to deploy in addition to more than 4,000 National Guard soldiers — were expected to make their first appearance on the streets Wednesday.

The mostly peaceful protests ignited over a sudden escalation in efforts to apprehend migrants who were in the country illegally.

Pockets of violence — including the burning of self-driving taxis and hurling stones at police — triggered a massive response from authorities using tear gas and other crowd-control weapons.

Trump won the election last year partly on promises to combat what he claims is an “invasion” by undocumented migrants.

He is now seizing the opportunity to make political capital, ordering the California National Guard to deploy despite Governor Gavin Newsom’s objections, the first time a US president has taken such action in decades.

Trump then tested the constitutional limits of his power even further by ordering about 700 Marines — a force designed primarily for combat in foreign wars — to the scene.

“If our troops didn’t go into Los Angeles, it would be burning to the ground right now,” Trump insisted on social media Wednesday, without evidence.

The White House later doubled down on that rhetoric.

“President Trump will never allow mob rule to prevail in America,” White House Press Secretary Karoline Leavitt told a briefing.

“The most basic duty of government is to preserve law and order, and this administration embraces that sacred responsibility.”

Governor Newsom, a Democrat, has charged that Trump is seeking to escalate the confrontation for political gain.

“Democracy is under assault right before our eyes,” he said in a televised address late Tuesday. “California may be first, but it clearly won’t end here.”

Trump has expressed support for a call by one of his top officials to arrest Newsom, who is seen as a potential Democratic presidential candidate in 2028, when Trump will be required by the constitution to step down.

– Nationwide protests growing –

Despite Trump’s threats to deploy the National Guard to other Democratic-run states over the objections of governors, protesters appear undeterred.

Thousands marched in New York and Chicago late Tuesday.

Republican Texas Governor Greg Abbott announced he was deploying the state’s National Guard to counter a protest announced for San Antonio on Wednesday.

Demonstrations were also planned Wednesday in New York, Seattle and Las Vegas ahead of what organisers say will be a nationwide “No Kings” movement on Saturday, when Trump will attend a highly unusual military parade in the US capital.

In a speech at an Army base on Tuesday, Trump warned that any protests during the Washington parade would face “very heavy force.”

The parade, featuring warplanes and tanks, has been organised to celebrate the 250th anniversary of the founding of the US Army but also happens to be the day of Trump’s 79th birthday.

The last large parade in Washington was in 1991 after the first Gulf War.

– ‘Inflamed’ situation –

The Trump administration is painting the protests as a violent threat to the nation, requiring military force to support regular immigration agents and police.

Trump on Tuesday cited a “full-blown assault on peace, on public order and national sovereignty” from a “foreign enemy.”

Protesters and the beleaguered Democratic opposition party say Trump is manufacturing a crisis that has little to do with expelling criminals in the US illegally.

Newsom said Trump “inflamed” the situation and went “well beyond his stated intent to just go after violent and serious criminals. His agents are arresting dishwashers, gardeners, day laborers and seamstresses.”

In the Atlanta suburb of Brookhaven, dozens of demonstrators waved American and Mexican flags and held signs against US Immigration and Customs Enforcement (ICE), the federal agency that has ramped up arrests and deportations of migrants under Trump.

“You got people that are being arrested on the street by (immigration) agents that don’t wear badges, wear masks… it makes me really angry,” 26-year-old protester Brendon Terra told AFP.