Migrants form a human chain to help fellow migrants cross the Suchiate river. Image Credit: REUTERS

Washington - The United States said on Monday it will send over 5,200 troops to help secure the border with Mexico, a far larger-than-expected deployment as President Donald Trump hardens his stance on immigration ahead of Nov. 6 mid-term elections.

The deployment will create an active-duty force comparable in size to the U.S. military contingent in Iraq, as Trump's administration draws attention to a caravan of migrants that is trekking through Mexico toward the United States.

General Terrence O'Shaughnessy, the head of U.S. Northern Command, said 800 U.S. troops were already en route to the Texas border and more were headed to the borders in California and Arizona.

Migrants, part of a caravan traveling to the U.S., stand in line to climb a little hill after crossing the Suchiate river, a natural border between Guatemala and Mexico. REUTERS

"The president has made it clear that border security is national security," O'Shaughnessy said, as he detailed a much larger deployment that the 800 to 1,000 troops predicted by U.S. officials last week.

O'Shaughnessy said some soldiers would be armed although it was unclear who, beyond U.S. military police, might need those weapons. U.S. officials have stressed that the troops would not police the border and instead carry out support roles like building tents and barricades, and flying U.S. customs personnel to locations along the border.

Trump railed against illegal immigration to win the 2016 U.S. presidential election and has seized on the caravan of Central American migrants at campaign rallies in the run-up to next week's vote, firing up support for his Republican Party.

Trump plans 'tent cities' at border

Trump said the United States would build "tent cities" to house migrants seeking asylum, rather than releasing them while they await court decisions.

Trump says in an interview with Fox News host Laura Ingraham that if any of the migrants, who are still hundreds of miles away, do make it to the border and apply for asylum, as they're legally entitled, the U.S. plans to "hold them until such time as their trial takes place."

Trump says: "We're going to build tent cities. We're going to put tents up all over the place ... and they're going to wait."

Under current protocol, migrants who clear an initial screening are often released until their cases are decided in immigration court, which can take several years.

Trump said detaining asylum seekers while their cases are being decided would discourage others from following suit.

Armed Soldiers 

If the Republicans lose control of the House of Representatives or the Senate, it could become much harder for Trump to pursue his policy agenda in his remaining two years in office.

According to a Pew Research Center survey conducted in late September and early October, 75 percent of Republican voters said illegal immigration is a very big problem, compared with 19 percent of Democratic voters.

Although Trump's supporters in Congress praised the deployment of troops, the American Civil Liberties Union derided it as a political stunt.

"President Trump has chosen just before midterm elections to force the military into furthering his anti-immigrant agenda of fear and division," said Shaw Drake, policy counsel for the American Civil Liberties Union Border Rights Center in El Paso, Texas.

Trump said on Twitter on Monday that the military would be waiting for the procession -- suggesting a far more direct role in confronting the migrants than the Pentagon described.

"Many Gang Members and some very bad people are mixed into the Caravan heading to our Southern Border," Trump tweeted.

"Please go back, you will not be admitted into the United States unless you go through the legal process. This is an invasion of our Country and our Military is waiting for you!" he added.

Trump administration officials have been discussing other options to address the caravan and a surge in border crossings, including having Trump use his authority under the Immigration and Nationality Act to declare certain migrants ineligible for asylum for national security reasons.

Officials said no decisions had been made.

Kevin McAleenan, the U.S. commissioner of Customs and Border Protection, said a group of approximately 3,500 immigrants were traveling through southern Mexico with the intent of reaching the U.S. border.

A second caravan of about 3,000 people were at the Guatemala-Mexico border, McAleenan said.

At the same time, over the last three weeks, border agents have encountered nearly 1,900 people per day either crossing the border illegally or presenting themselves at ports of entry, with over half of them being children alone or parents and children traveling together, McAleenan said.

"We are already facing a border security and humanitarian crisis at our southwest border," he said.

2nd group of migrants enters Mexico 

Hundreds of Central Americans following in the footsteps of a thousands-strong migrant caravan making its way toward the U.S. border crossed a river from Guatemala into Mexico on Monday, defying a heavy Federal Police presence deployed to patrol that country's southern frontier.

Some migrants have abandoned the journey, deterred by the hardships or the possibility instead of making a new life in Mexico. Others joined it in southern Mexico.

The migrant caravan slowly advancing through southern Mexico is demanding the Mexican government help its 4,000 participants reach Mexico City even as a smaller group of Central Americans entered the country, presumably with the intention of joining it.

Worn down from long miles of walking and frustrated by the caravan's slow progress, some migrants have been dropping out and returning home or applying for protected status in Mexico. Conscious of that frustration, its representatives demanded "safe and dignified" transportation to the capital Monday after the group arrived in the Oaxaca state town of Niltepec.

A Mexican police helicopter flies over migrants. REUTERS

The Mexican government has shown no inclination to assist, however, with the exception of its migrant protection agency giving some of the caravan's stragglers rides to the next town over the weekend.

Pueblo Sin Fronteras, a group supporting the caravan, has said it hopes to hold meetings in Mexico City with federal lawmakers and authorities as well as representatives of the incoming government to discuss migrants' rights and the caravan's future.

But Mexican officials seem intent only on seeing the caravan melt away as it travels toward the U.S. border. The government regularly trumpets the number of migrants who have applied for refugee status or asked to return to their home countries.

On Monday, the Federal Police aggressively tried to turn back hundreds more migrants who crossed the Suchiate River to enter Mexico from Guatemala.