President Trump on Thursday threatened to close off the southern border, telling reporters that he would “close entry into the country” if immigration gets “uncontrollable.”

“If we find that it gets to a level where we’re going to lose control or people are going to start getting hurt, we will close entry into the country for a period of time until we can get it under control,” he said.

Speaking to reporters while in Florida for the holiday, Trump added that he meant the “whole border,” though he appeared to be referring only to the southern border.

“We’re either going to have a border or we’re not,” he said, adding that Mexico wouldn’t “be able to sell their cars” into the U.S, reported by The Hill.

Earlier this week traffic lanes near a key port of entry in San Diego were temporarily shut down.

“Two days ago, we closed the border. We actually just closed it,” Trump said. “We said, ‘Nobody’s coming in.’ Because it’s out of control.”

Homeland Security Secretary Kirstjen Nielsen said Monday that the lanes were shut down because a large number of migrants were planning to “rush the border.”

President Trump also said he has given the thousands of active-duty troops he sent to the border before the Nov. 6 midterm elections the “OK” to use lethal force against migrants “if they have to.” And he said Homeland Security Secretary Kirstjen Nielsen, whom he has faulted for not being tough enough on immigration, is “in there trying.”

“It’s a tough job,” he said.

The president has claimed that a group of Central American asylum seekers traveling through Mexico and toward the U.S. border present a national security threat.

“You’re dealing with a minimum of 500 serious criminals, so I’m not going to let the military be taken of advantage of,” Trump said Thursday. “I have no choice. Do I want that to happen? Absolutely not. You’re dealing with rough people.”

“The caravans will not be permitted to enter the United States,” Secretary of State Mike Pompeo said Thursday. “There are real dangers to the safety and human rights of migrants from those who would prey on them.”

Trump’s border threat came days after a federal judge put the administration’s asylum policy on hold. Under that new policy, Trump declared no one could apply for asylum except at an official border entry point. Some ports of entry are already facing huge backups, with people waiting for weeks.

Trump asserted that there are “fistfights all over the streets” in Tijuana, Mexico, and that “these are not like normal, innocent people.”

“These are people you talk to them and they start a fistfight,” he said. “I don’t want that in this country,” according to Fox News.

The people of Tijuana “opened up with wide arms” to welcome the caravan, Trump said, and “now they’re going crazy to get them out … because bad things are happening.”

In the past week, city officials have arrested three dozen caravan members for drug possession, public intoxication, disturbing the peace and resisting police, and said they would be deported to their home countries. Many also say the actions of a few are tarnishing the image of the roughly 4,000 migrants who are camped in Tijuana.

Trump also confirmed Thursday that he had authorized troops at the border to use force against immigrants if necessary.

Trump said that if U.S. officials “find that it’s uncontrollable, if we find that it gets to a level where we are going to lose control or where people are going to start getting hurt, we will close entry into the country for a period of time until we can get it under control. The whole border.”

Sources: AP, Fox News, The Hill