The US military has received a request for active-duty troops on the US-Mexico border, a US official said on Thursday, after President Donald Trump said he was “bringing out the military” to guard against a caravan of Central American migrants and refugees.

The caravan is still more than 1,500km from the US border, but a US official who spoke anonymously to Reuters said the military was examining the request, which could require deploying between 800 and 1,000 active-duty troops to the border to assist with logistics and infrastructure.

Thousands of US-bound Central American men, women and children seeking to escape violence, poverty and government corruption in their home countries continued their journey on Thursday. Under a full moon during pre-dawn hours, they walked from Mapastepec, close to the Guatemala border in southern Mexico. A town official said there had been 5,300 migrants in Mapastepec on Wednesday night.

The US official speaking to Reuters, said that any US troops deployed to the border would not be involved in “law enforcement” activities, owing to its prohibition by a federal law dating to the 1870s.

That law restricts the use of the army and other main branches of the military for civilian law enforcement on US soil unless specifically authorised by Congress. But the military can provide support services to law enforcement and has done so on occasion since the 1980s.

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AFP news agency, citing an unnamed US official, reported that the Pentagon is expected to deploy “several hundred” troops to the border. The official, speaking on the condition of anonymity, told the news agency that the troops would be used mainly to provide logistical support including tents, vehicles and equipment.

‘Zero tolerance’

Trump has taken a hard line towards immigration since becoming president last year. On Monday, Trump said he had alerted the Border Patrol and the US military that the migrant caravan was a national emergency.

The initial wave of migrants and refugees, who left Honduras less than two weeks ago, has been followed by other groups, who are now making their way through Guatemala.

White House officials did not immediately respond to requests for comment on Trump’s comments regarding a military deployment and a national emergency. The president has also threatened to cut US aid to the Central American countries if the migrants and refugees are not stopped.

Central American migrants and refugees walking to the US start their day departing Ciudad Hidalgo, Mexico, on Sunday [Moises Castillo/AP Photo]

Trump has sought to make the caravan and immigration major issues ahead of the November 6 midterm election, in which his Republican party is trying to maintain control of the House of Representatives and the Senate.

It is not new territory for Trump, who pledged during the 2016 presidential race to build a wall along the southern US border with Mexico. However, funding for his signature campaign promise has been slow to materialise.

In April, frustrated by lack of progress on the wall, Trump ordered the National Guard to help secure the border in four southwestern states. There are currently 2,100 National Guard troops along the borders of Texas, New Mexico, Arizona and California.

Also in April, Trump raised the prospect of sending active-duty military forces to the border to block immigrants, raising questions in Congress and among legal experts about troop deployments on US soil.

‘Not a national emergency’

The president has been criticised by immigrant advocates and rights groups over his “zero tolerance” policy at the border. Earlier this year, Trump was forced to abandon his administration’s controversial practice of separating families at the border after public outcry.

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Caravans coming from Central America have made their way to the US border for years without much fanfare. Migrants and refugees often leave in groups for safety purposes. This month’s caravan is unusual for its large size, however, and those travelling north seem to be so far undeterred by the president’s threats.

A migrant woman rests roadside with her child while travelling with a caravan of thousands from Central America en route to the United States as they make their way to Mapastepec from Huixtla [Adrees Latif/Reuters]

In April, a caravan that had about 1,500 people at its peak also caught the ire of Trump. Many of its participants attempted to stay in Mexico and only a few hundred people continued to the US border, seeking asylum at an official port of entry, rights groups said.

According to the New York Times, about 400 were referred to the US for “credible fear” interviews. Many who passed that step are still awaiting further immigration hearings.

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Rights groups have slammed the president’s reaction to the latest caravan as a “scare” tactic, especially before the midterm elections.

Earlier this week, Amnesty International said in a statement on Twitter that “the caravan is not a ‘National Emergy’ or a security threat.”

It added, “Many of these individuals are fleeing violence in their home country with the intention of seeking asylum. These are people. They have human rights. You cannot scare us away from the truth.”

Rights groups have also said the government responses to and threats made against the caravan may violate international law.