President Donald Trump on Tuesday said he planned to use USA military forces to protect the nation's southern border with Mexico until there is a border wall and "proper security". "That's a big step", Trump told reporters gathered at the White House.

U.S. President Donald Trump speaks while participating in a tour of U.S. -Mexico border wall prototypes near the Otay Mesa Port of Entry in San Diego, California.

Trump has railed against more than 1,200 Central American migrants on a 2,000-mile (3,200-km) journey from the Mexico-Guatemalan border, and reiterated threats to derail the North American Free Trade Agreement (NAFTA) if they are not stopped.

Trump has stepped up his immigration rhetoric in recent days and his administration has moved to further crack down on people, who are in the US illegally.

"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.

The "caravan" of mostly Central American migrants making its way through Mexico reportedly stopped Monday at a local park, as the marchers decide where and when to proceed. The President had threatened to end the NAFTA agreement if the Mexican government did not stop the caravan and to end USA aid to Honduras. -Baltic Summit, asserting that he had a meeting with Defense Secretary James Mattis "in a little while" to discuss the militarization of the border.

"It's sad for the people in the caravan and it's sad for the people in the United States".

Brett McGurk, the special USA envoy for the global coalition against Islamic State, said: "We are in Syria to fight ISIS. Mexico is our neighbour, and our friend", Bush insisted in 2006 in a speech on immigration reform that nonetheless announced a large increase in the number of border patrol agents and the deployment of up to 6,000 National Guard membersin a two-year operation dubbed Jump Start. The deployments came after border patrol agents complained they were undermanned, and worries were growing over a spate of cross-border flights of ultralight aircraft ferrying drugs across the border.

In 2010, President Barack Obama sent some National Guard troops to the U.S.

Some members of Congress said they were uncomfortable with the idea of using the military at the border.

"I think we should put that new law to a vote in the Senate as soon as possible", he said on Twitter.

The president has recently floated the idea of having the Pentagon, at least in part, pay for the wall along the U.S./Mexico border, which he has previously insisted Mexico would fund.

In spite months of efforts, no immigration deal has emerged in the Republican-led Congress, where lawmakers are not expected to pass much major legislation ahead of November's midterm congressional elections.