President Donald Trump reportedly is sending 5,000 military troops to the border with Mexico in response to the latest caravan of Central American migrants marching north, intent on entering the U.S.

“Roughly 5,000 U.S. troops will be deploying to the southern border in response to the migrant caravan pushing north through Mexico, a U.S. official confirmed to Fox News,” Fox reporter Lucas Tomlinson said.

“Some of the troops will be deploying as early as Tuesday. The reinforcements headed to the U.S.-Mexico border are support troops, not combat troops. They will include engineers, aviation and medical personnel.”

Later on Monday, Customs and Border Protection (CBP) Commissioner Kevin McAleenan, U.S. Northern Command and North American Aerospace Defense Command Gen. Terrence John O’Shaughnessy, and Assistant Secretary of Defense for Homeland Defense and Global Security Kenneth P. Rapuano will provide further details on the deployment during a joint news conference.

The deployment is to provide logistical support to CBP and National Guard personnel already on the border.

An 1878 federal law known as the Posse Comitatus Act bars military units from being used to enforce civilian law.

Related: ‘Walls Work’: Portion of Border Project Unveiled as Migrant Remain Determined to Reach U.S.

Secretary of Homeland Security Kirstjen Nielsen said Sunday her message for those in the caravan is this: “Do not come. You will not be allowed in. There is a right way to emigrate to the United States, and this is not it. This caravan is not getting in … Those who choose to enter illegally will be stopped.”

During an interview on “Fox News Sunday” with Chris Wallace, Nielsen added, “We have a crisis at the border right now. I think what the president is making clear is every possible action, authority, executive program, is on the table to consider, to ensure that it is clear that there is a right and legal way to come to this country, and no other ways will be tolerated.”

“Do not come. You will not be allowed in. There is a right way to emigrate to the United States, and this is not it. This caravan is not getting in,” said Nielsen.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

Among Trump’s first acts when he took office as president was issuing an executive order travel ban on individuals from half a dozen Muslim countries with histories of either actively aiding terrorists or tolerating their presence.

Multiple legal challenges sent the travel ban all the way to the Supreme Court, which — on a 5-4 decision issued June 26 — upheld Trump’s authority as president to bar entry to any noncitizen for any reason or no reason at all.

What authority allows Trump to send such a large contingent of U.S. troops to the border will almost certainly be among the first questions journalists will ask at the Pentagon’s afternoon news conference.