President Trump said Tuesday the military would be guarding the U.S.-Mexico border until a border wall can be constructed and “proper security” put in place.

"We have very bad laws for our border and we are going to be doing some things, I’ve been speaking with Gen. Mattis, we’re going to be doing things militarily,” Trump said Tuesday before a working lunch with Baltic leaders. “Until we can have a wall and proper security, we are going to be guarding our border with the military. That’s a big step. We really haven’t done that before, and certainly not very much before.”

The president was referencing Secretary of Defense Jim Mattis. The Pentagon was waiting for more details immediately after Trump's announcement.

If Trump did send troops to the U.S.-Mexico border, he would not be the first president to do so. President Barack Obama dispatched 1,200 National Guard troops to the southern border in 2010, and President George W. Bush sent more than 6,000 troops to the border between 2006 and 2008.

Texas Gov. Rick Perry, now Trump’s energy secretary, ordered 1,000 National Guard troops to the southern border in 2014 due to a flood of unaccompanied minors coming into the U.S. from Central America.

President Trump: "Until we can have a wall and proper security, we're going to be guarding our border with the military. It's a big step." pic.twitter.com/VFW9yaCikA — NBC News (@NBCNews) April 3, 2018

He also lamented the number of immigrants coming into the U.S. illegally.

"We cannot have people flowing into our country illegally, disappearing, and by the way never showing up for court,” he said. “So the court case would be set for two years or three years if you can believe this, and they never show up, for the most part, very rarely do they show up.”

During the 2016 campaign, Trump promised to build a wall across the country’s southern border. The president has continued to press Congress for federal dollars to build the structure, and reportedly suggested money for the border wall should come from the Defense Department, as the U.S.-Mexico border is a “national security” issue.

The president hinted on Twitter about using the defense budget to build the wall across the southern border last month.

“Because of the $700 & $716 Billion Dollars gotten to rebuild our Military, many jobs are created and our Military is again rich. Building a great Border Wall, with drugs (poison) and enemy combatants pouring into our Country, is all about National Defense. Build WALL through M!” Trump tweeted.



Because of the $700 & $716 Billion Dollars gotten to rebuild our Military, many jobs are created and our Military is again rich. Building a great Border Wall, with drugs (poison) and enemy combatants pouring into our Country, is all about National Defense. Build WALL through M! — Donald J. Trump (@realDonaldTrump) March 25, 2018



Travis Tritten contributed to this report.