Updated

President Trump said Wednesday that his administration will “be taking strong action today” on the Mexico border, a day after he said that he wants to send the military to secure it until a wall is built.

In a tweet, Trump said that the U.S. border laws “are very weak” compared to Mexico and Canada, and accused Democrats of wanting immigrants “to pour into our country unchecked.”

“We will be taking strong action today,” he added.

His tweet came a day after he told reporters that he wants to guard the border with the military until a wall on the southern border was buit.  

“Until we can have a wall and proper security, we’re going to be guarding our border with the military,” he said. “That's a big step, we really haven’t done that before, or certainly not very much before.”

A White House official revealed later Tuesday to Fox News that the plan considered by Trump would be a “substantial” mobilization of the National Guard.

Trump appears to have been partly motivated by a caravan of more than 1,000 Central American migrants heading toward the U.S. border. Trump had threatened to end the North American Free Trade Agreement (NAFTA) and to cut foreign aid to countries such as Honduras, from where many of the migrants originate, if the caravan is not stopped.

TRUMP SAYS THE MILITARY WILL SECURE THE SOUTHERN BORDER UNTIL WALL CAN BE BUILT 

Trump said Tuesday that he believes the caravan is being broken up after he had a converation with Mexican officials.

Homeland Security Secretary Kirstjen Nielsen said that she had been advised by Mexican officials that “the caravan is dissipating” and that several hundred migrants had been repatriated.

Former Presidents Barack Obama and George W. Bush had deployed the National Guard to the border in response to security issues. The Associated Press reported that the White House appeared to be considering a model similar to a Bush-era operation, where in 2006 6,000 National Guard troops were sent to assist the border patrol with non-law enforcement duties while additional border agents were hired and trained. 

The Guard members were used for surveillance, communications, administrative support, intelligence, analysis and the installation of border security infrastructure.

Trump has intensified his focus on border security as he has struggled to secure funding for the wall, estimated to need approximately $25 billion. In the omnibus bill signed by Trump last month, $1.6 billion was included for technology and some replacement of existing border fencing -- although it excluded the prototypes Trump recently viewed in California.

Trump briefly considered vetoing the legislation both over its lack of funding for the wall and also the failure to include a fix for the expiring Deferred Action for Childhood Arrivals (DACA) program that granted protection for illegal immigrants brought to the country as children. He has also floated the idea of getting the Pentagon to fund the wall.

Fox News’ John Roberts and The Associated Press contributed to this report.