The Pentagon said Monday that it would order 5,200 active-duty soldiers to the Southwestern border to help fortify the area as a caravan of Central American migrants slowly heads north through Mexico.

A San Antonio-based command, U.S. Army North, will help with the mission to assist the Homeland Security Department along the Texas-Mexico border. Air Force Gen. Terrence O’Shaughnessy, chief of the U.S. Northern Command, said 800 soldiers already were en route to Texas.

“They’re coming from Fort Campbell. They’re coming from Fort Knox,” he said at a news conference in Washington. “They’re going to continue their training, and they’re ready to deploy to actually be employed on the border.”

In a tweet Monday, President Donald Trump warned the convoy of migrants, most of them Hondurans and Guatemalans, that they would not be allowed in the country, calling them an invasion force and adding, “our Military is waiting for you!”

The soldiers, like the National Guard troops already on the border, will be armed and allowed to use their weapons in self-defense, but federal law does not allow the military to detain or confront immigrants.

Army North, based at Joint Base San Antonio-Fort Sam Houston, said “military personnel will provide a range of support” for U.S. Customs and Border Protection, including planning assistance, engineering support, and fixed- and rotary-wing aircraft to move federal agents.

The Army also will provide “medical teams to triage, treat and prepare for commercial transport of patients, command and control facilities, temporary housing for CBP personnel and personal protective equipment for CBP personnel,” the statement said. Engineering support will include “temporary barriers, barricades and fencing,” it said.

O’Shaughnessy said the military, working alongside CBP officers, would focus first on hardening the border in Texas, followed by Arizona and California. He said the Pentagon already has sent 22 miles of concertina wire to the border and has enough additional wire to cover 150 miles.

The deployments will include three combat engineer battalions, O’Shaughnessy said. He highlighted the deployment of helicopters, which will have night-vision capabilities and sensors, saying, “We’ll be able to spot and identify groups and rapidly deploy CBP personnel where they are needed.”

Army North said the U.S. Northern Command would serve as the lead for “the duration of the operation” but did not elaborate.

Joint Base San Antonio-Lackland will be among the staging areas used by soldiers who are part of the border mission, a Pentagon spokesman, Navy Capt. Bill Speaks, said Tuesday.

Fort Hood, meanwhile, reported that parts of its 89th Military Police Brigade and 36th Engineer Brigade would be dispatched to the border. A post spokesman, Tyler Broadway, did not know how many soldiers would be involved or when operations would begin.

As directed by the Pentagon, III Corps and Fort Hood will deploy soldiers, equipment, and resources to support the Department of Homeland Security along the Southwestern border. The Army will bring along such items temporary barriers, barricades, and fencing, logistics support to move U.S. Customs and Border Protection personnel, and medical teams to triage the sick and injured. It also will help prepare for commercial transport of patients and preparing meals in the field.

The president’s order, coming eight days before the midterm elections, will add to a National Guard presence on the border, bringing the total number of troops to just under 7,300.

Citing a Defense Department official, Newsweek reported that the active-duty contingent could reach 7,000, with another 7,000 on standby and able to join the force on 24 hours’ notice. The reserve units are to include dog handlers, linguistics personnel and more aviation units, according to documents the magazine reviewed.

Customs and Border Protection Commissioner Kevin McAleenan said planners were preparing to respond to any large group trying to force an entry at any point on the border.

“As information on the approach of a large group at a port of entry is available, we have at the ready 1,000 CBP officers, including 250 tactical enforcement officers and mobile response team professionals with training on managing contingencies including riot control.”

The Washington Post has reported that Trump is preparing to announce a major immigration crackdown Tuesday, in which he is expected to invoke emergency powers to bar migrants from crossing the border and asking for asylum — a move that almost certainly would result in immediate legal challenges. The U.S. is a party to the United Nations convention on refugees, which holds in part that countries should not pose penalties on refugees who enter unlawfully to ask for asylum.

Trump has sought to make illegal immigration a defining theme for the midterm and has made the migrant caravan a regular topic at political rallies and tweets. He has said, without evidence, that gang members, “Middle Easterners” and “very bad people” are among those making their way north.

Most are fleeing poverty and crippling gang violence, and many have said they intend to surrender at the border to claim asylum. The main group of about 3,500 is still in southern Mexico, McAleenan said. From a peak of nearly 7,000, its numbers have thinned. At least 1,000 caravan members have applied for asylum in Mexico, authorities say.

McAleenan said a second group at the Guatemalan border with Mexico has about 3,000, “made up of family units and unaccompanied children who have placed themselves in the hand of violent human smugglers paying $7,000 per person to make the journey.”

National Guard units in Texas, New Mexico, Arizona and California had 2,092 troops on the border as the week began, but the number of soldiers was far lower than what originally had been projected when Trump ordered their deployment in early spring. At one point, the administration said it would deploy around 4,000 guard troops to the Lower Rio Grande Valley.

The Texas Guard, the nation’s largest, with around 21,292 soldiers and airmen, has more than 1,000 personnel stationed along the border, said a spokesman, Josh Amstutz. That number is up from the initial number of personnel mobilized this past spring.

The overall number of migrants crossing the border illegally dropped to a historic low in the year after Trump took office in 2017, part of a steady decline from a peak of more than 1.6 million in 2000. Though total apprehensions rose slightly this year to 396,579, the greatest source of frustration to the Trump administration has been the change in who is coming, from mostly Mexican men to a large jump in Central American families seeking asylum.

More than 16,650 families were apprehended at the border in September, a 30 percent jump from August, bringing the total number of families coming here illegally to 107,212 during the fiscal year ending in September — a 42 percent increase from the previous fiscal year.

The administration for months has blamed federal rules and congressional “loopholes” for preventing it from detaining most Central American families until they are deported and has pushed to change them. It is trying to undo a landmark 1997 lawsuit settlement that prevents the prolonged detention of children and to change a 2008 bipartisan law meant to curb human trafficking.

It has blamed the two for its “zero-tolerance” policy this summer that resulted in the separation of more than 2,600 children from their parents, many of whom were deported while their children remained in U.S. shelters. Trump ended the policy in June after facing widespread outrage, and a federal judge in California ordered the government to reunify the families, a process that is still ongoing.

The government has few options in limiting the legal right to ask for asylum. The administration said many families are released to pursue their cases and then never show up to court, or, if they do, that their cases take months or years to process in the record-backlogged system.

U.S. Rep. Henry Cuellar, D-Laredo, expressed support for the expanded military mission, saying in a statement, “I strongly believe that this starts with ensuring that we implement policies and utilize technology that will have long-term, significant outcomes on the area in a safe and reliable way. This partnership with DOD will help enhance CBP capabilities at, and between, our ports of entry.”

National Guard operations on the border were launched by Presidents George W. Bush and Barack Obama, as well as Texas governors who include Rick Perry and Greg Abbott. Trump’s original guard deployment order resembled Obama’s Operation Phalanx, which started in 2010 and involved 1,200 soldiers, but it’s been far smaller than Bush’s Operation Jump Start, which saw 6,000 troops descend on the border in 2006.

The administration last week began freeing migrant families unrelated to the caravan who were apprehended at the Southwestern border en masse, saying it no longer had the resources to complete their “post release plans” and drop them at bus stations or otherwise coordinate their travel plans. It has said it doesn’t have the capacity to detain them, though the three family detention centers had only 1,977 beds occupied last week out of a funded capacity of 2,500.

The mass releases are overwhelming nonprofit shelters from McAllen to San Diego and have led to speculation among advocates and Border Patrol agents that space is being made in the detention centers to hold families in the caravan attempting to pursue asylum. Some migrant advocates have even said it could be part of an effort to suggest instability at the border.

sigc@express-news.net