President Trump told reporters aboard Air Force One Thursday he plans to send "anywhere from 2,000 to 4,000" National Guard troops to the southwest border as soon as possible as a large caravan of migrants continue to travel through Mexico toward the US.
"We'll probably keep them or a large portion of them," until a wall is built, he said.
Trump's comments came a day after his administration announced it was working with governors to deploy the National Guard, a plan that was unveiled shortly after the president had threatened to send the military to the border.
As for the cost, he told reporters that his administration is "looking at it."
"The threat is real," Homeland Security Secretary Kirstjen Nielsen told reporters Wednesday while announcing the plan. "The president has directed the Department of Defense and the Department of Homeland Security to work together with our governors to deploy the National Guard to our southwest border to assist the Border Patrol."
Nielsen made the announcement at a White House press briefing after President Trump threatened on Tuesday to send the military to the border to stop the group of mostly Central American migrants.
But she lacked specifics in terms of timing and cost, saying details were still being worked out and that she didn't want to "get ahead" of the state governors affected by the plan. Nielson did add, however, that the number of troops "will be as many as is needed to fill the gaps."
However, a spokesman for California Gov. Jerry Brown told BuzzFeed News he was only contacted by the White House regarding the plan Wednesday, the same day it was announced.
It wouldn't be the first time a president has deployed National Guard troops along the southern border, but Nielsen declined to say if this deployment would be larger or smaller than in years past.
The California National Guard said it would review the request from the Department of Homeland Security, just like it did in 2010 under President Obama and in 2006 under President George W. Bush.
The department, however, appeared to have questions on specifics as well.
"We look forward to more detail, including funding, during, and end state," Lt. Col. Tom Keegan told BuzzFeed News in an email.
In his presidential memorandum released Wednesday night, Trump gave the defense secretary, head of homeland security, and the attorney general 30 days to submit an "action plan" outlining how the agencies will go about beefing up border security.
Nielsen also spoke with Mexico's Secretary of Foreign Affairs Luis Videgaray Wednesday and, according to a statement issued by Mexico's government, were reassured that the National Guard would only be assisting US Customs and Border Patrol.
According to Mexico, Nielsen also informed them that National Guard troops would not be armed or conducting immigration control enforcement duties — details White House officials and Nielsen had declined to provide when announcing the operation earlier in the day.
Some governors that would be affected by the operation appeared to welcome the news from the White House.
"Washington has ignored this issue for too long and help is needed," he said in a tweet welcoming the news.
And in a statement, Texas Gov. Greg Abbott said he's already maintained a presence of troops on the border.
"Today's action by the Trump Administration reinforces Texas' longstanding commitment to secure our southern border and uphold the Rule of Law, and I welcome the support," he said.
Asked why the president is pushing forward with the plan, Nielsen would only say that Trump had grown "frustrated" with the current border situation.
Nielsen said that after experiencing 40-year lows, the number of immigrants crossing illegally over the border into the US had increased, saying some of the migrants were drawn by lax immigration laws and so-called catch-and-release practices of border patrol agents.
"Why not attempt the journey if you have no belief you'll ever be caught?" she said.
However, numbers released by CBP have shown detentions on the border with Mexico have been on a downward trend. At the end of the 2017 fiscal year, for example, the agency reported 310,531 immigrant apprehensions, the lowest that has been seen by the agency since 1971.
And although CBP reported an increase in detentions in February and March, when compared to last year, there significant drops in the number of detentions along the Southwest border between October 2017 to January 2018.
So far this fiscal year, according to numbers released Wednesday, there was a 13% decrease in border detentions when compared to the same period last year.
Blaming Congress for weak immigration laws, Nielsen said the president would also be pressing lawmakers to close loopholes that enable migrant families to enter and remain in the US.
The Trump administration's attention to the caravan of migrants fleeing Central America came after a BuzzFeed News report on the group of more than 1,000 people was covered by Fox News over the weekend.
"We are preparing for the military to secure our border between Mexico and the United States," Trump told reporters on Tuesday, adding he was meeting with Secretary of Defense James Mattis.
In a statement responding to the president's National Guard order, Attorney General Jeff Sessions referred to the "migrant caravan" and the president's declaration that it needed to be stopped.
"The president was clear that this caravan needed to be stopped before it arrived at our southern border, and his efforts now appear to be successful," Sessions said. "But let me be clear as well: we will not accept the lawlessness of these types of efforts and those who choose to violate our laws, and those who conspire to assist others to violate our laws, will face criminal prosecution."
Sessions also said he would be announcing additional Department of Justice initiatives to bolster the president's efforts and "to restore legality to the southern border."
However, White House press secretary Sarah Huckabee Sanders on Wednesday rejected the idea that Trump was motivated by the Fox News report.
"I think it has everything to do with protecting the people the of the country," she said. "The president has been talking about it for years, since he started on the campaign trail."
Trump has also suggested that negotiations on the North American Free Trade Agreement (NAFTA) would be affected by Mexico's actions to stop the massive group of people, many of whom told BuzzFeed News they were fleeing violence and hoping to ask for asylum in the US.
"I told Mexico yesterday that because the fact that their laws are so strong that they could do things about it," Trump said. "I said, 'I hope you're going to tell that caravan not go get up to the border.'"
Meanwhile, Mexican President Enrique Peña Nieto on Thursday issued a rebuke of Trump's comments, including the US president's threat to use NAFTA negotiations to force Mexico to act on the caravan of migrants traveling through the country.
"We'll never negotiate with fear," Peña Nieto said.
Relations between countries, even allies, he said, have their challenges but, "they never justify threatening attitudes or lack of respect between nations."
Peña Nieto said he stood in support of the Mexican senate, which on Wednesday passed a resolution rejecting the US "militarization of the border." The resolution also called for Mexico to stop cooperating with the US on issues of immigration, transnational crime and drug trade, but Peña Nieto did not refer to that portion of the document.
"President Trump, if you want to reach agreements with Mexico, we are ready," Peña Nieto said in the video message. "If your recent statements come from a frustration at internal political issues, your laws, or your Congress, direct yourself to them, not to the Mexican people."