WASHINGTON, April 3 (Xinhua) -- U.S. President Donald Trump said Tuesday that he wants to use the military to guard the country's border with Mexico until his long-promised border wall is built.

"We are going to be guarding our border with our military," Trump told reporters during a lunch session at the White House with leaders of Estonia, Latvia and Lithuania.

"We're going to be doing things militarily until we can have a wall and proper security," the president said. "That's a big step."

Trump also said that he's spoken with Defense Secretary Jim Mattis about the idea.

The president has been lashing out at Mexico for allowing a group of Central American demonstrators, mostly from Honduras, to march toward the U.S. border, where many hope to seek asylum.

"The big Caravan of People from Honduras, now coming across Mexico and heading to our 'Weak Laws' Border, had better be stopped before it gets there," Trump tweeted early Tuesday.

Trump has recently reiterating his hardline stances on immigration, while repeatedly calling out Mexico over the border security and stressing the need for a border wall on the southern border.

The 1.3-trillion-U.S.-dollar spending bill, signed into law by Trump last month, only grants 1.6 billion dollars for border security measures, far short of what the administration has sought.

Trump has proposed using military funding to build the border wall but it's likely to face both political and legal challenges before the idea can be put into action.