Trump says military will guard border President Donald Trump said Tuesday he is directing the military to secure the southern border in lieu of a wall until it can be built.

President Donald Trump said Tuesday that he’s directing the U.S. military to secure the U.S.-Mexico border in lieu of, for now, a border wall.

“We’re going to be doing things militarily until we can have a wall and proper security.” Trump said.

Trump’s comments came as he sat next to Secretary of Defense Jim Mattis, who was reportedly at the White House for discussions around immigration. However, a defense official who spoke on the condition of anonymity had no immediate details as to how many troops would be used or what authorities they would have.

Mattis, Trump discuss using military funds for border wall Trump has suggested that part of the military's new budget surplus could be used to fund a border wall.

Speaking later in the day, Trump indicated Mattis would be part of an afternoon meeting to figure out how to address the ”horrible, horrible, very unsafe laws” for the border with Mexico.

The defense official noted one option could be similar to the 2006-2008 patrols U.S. military personnel conducted under Operation Jump Start.

Mounted Border Patrol agents are seen as President Donald Trump inspects border wall prototypes in San Diego, Calif., on March 13, 2018. (Mandel Ngan/AFP via Getty Images)

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In that operation, President George W. Bush called for up to 6,000 National Guard members to secure parts of the border. Eventually 29,000 military personnel from all over the country were involved in the mission, which had a projected cost of around $1.2 billion in then-year dollars.

In 2012, President Barack Obama deployed Army forces from Fort Bliss to the Tucson, Arizona, and El Paso, Texas, areas for Operation Nimbus, a joint operation between U.S. Northern Command and Customs and Border Patrol.

Per an Army press release at the time, military forces conducted “day and night reconnaissance missions using the Long Range Advanced Scout Surveillance System to detect, recognize, identify and geo-locate possible incursions, which they would then report to Border Patrol agents. Avenger Soldiers, using the Forward Looking Infrared system, and Soldiers monitoring Sentinel radar, also augmented border air incursion detection efforts.”

This story is developing and will be updated.