WASHINGTON: The Trump administration is planning to dispatch 800 or more active duty troops to the southern border at the direction of a president who has sought to transform fears about immigration into electoral gains in the midterms as a caravan of thousands of migrants makes its way through Mexico.

Defence Secretary Jim Mattis is expected to sign an order sending the troops to the border, bolstering National Guard forces already there, a US official said Thursday. The action comes as President Donald Trump has spent recent days calling attention to the caravan of Central Americans slowly making their way by foot into southern Mexico, but still more than 1,000 miles from US soil.

Trump, who made fear about immigrants a major theme of his 2016 election campaign, has been eager to make it a top issue heading into the Nov. 6 midterm elections, which will determine control of Congress. The president and senior White House officials have long believed the issue is key to turning out his ardent base of supporters.

The additional troops would provide logistical and other support to the Border Patrol, said the official, who spoke on condition of anonymity to discuss a plan that had not yet been finalised and formally announced.

It’s not unusual for the National Guard to help with border security. Although active duty troops are sometimes called on for domestic emergencies like hurricanes or floods, they rarely deploy to the southern border. Fears of militarising the border were fanned by a May 1997 incident in which a Marine on a counter-narcotics mission shot to death an 18-year-old who was herding goats in Redford, Texas.

In the current situation, active duty troops will not be on armed security missions that could lead to a similar incident.

The additional members of the military would assist the Border Patrol by providing things such as vehicles, tents and equipment. There already are about 2,000 National Guard troops there under a previous Pentagon arrangement.

Trump has used the caravan to bolster his election-season warnings that the US is being infiltrated by illegal immigrants “pouring across the border,” whom he has painted with a sinister brush.

He has claimed without any apparent basis in fact that “Middle Easterners” were among the shirking group. At rallies and on Twitter, Trump has tried to portray the Democrats as pro-illegal immigration, even claiming, with no evidence, that Democrats had organised and paid for the caravan.

He tweeted Thursday that, “Democrat inspired laws make it tough for us to stop people at the border” and said he was using the military to respond to what he called a “National Emergency.”

The migrants in the sprawling caravan — once estimated by the United Nations to number more than 7,000 — are hoping to make it to the United States. Most are Hondurans, seeking to escape the poverty and violence that plagues the region.

The caravan swelled dramatically soon after crossing the Mexican border on Oct. 19, but sickness, fear and police harassment have whittled down its numbers. Since entering Mexico at its southernmost tip, the group has advanced roughly 95 miles.

Trump tweeted a direct message to the migrants Thursday, urging them to return home.

“To those in the Caravan, turnaround,” he wrote. “We are not letting people into the United States illegally. Go back to your Country and if you want, apply for citizenship like millions of others are doing!”

— AP