"I fully expect these tariffs to go on to at least the 5 percent level on June 10," acting White House Chief of Staff Mick Mulvaney said. | Evan Vucci/AP Photo trade Trump ‘deadly serious’ about Mexico tariffs, Mulvaney says

President Donald Trump is "deadly serious" about his threat to impose a 5 percent tariff on all goods from Mexico over his concerns of illegal immigration, Mick Mulvaney, the acting White House chief of staff, said Sunday.

"He is absolutely, deadly serious," Mulvaney said on Fox News Sunday. "I fully expect these tariffs to go on to at least the 5 percent level on June 10."


Trump last week tweeted the United States would impose a 5 percent tariff on all goods from Mexico "until such time as illegal migrants coming through Mexico, and into our Country, STOP."

Mulvaney doubled-down on that timeline Sunday, explaining that the White House "for months" has been talking about an "emergency situation" at the U.S.-Mexico border.

"The president is deadly serious about fixing the situation at the southern border," Mulvaney said.

The president tweeted last week the tariff would "gradually increase until the Illegal Immigration problem is remedied." The White House later clarified the tariff would increase to 10 percent on July 1; 15 percent on Aug. 1; 20 percent on Sept. 1; and 25 percent on Oct. 1.

"The reason we're doing things people don't expect is that we're facing things at the border we never experienced before," Mulvaney said on NBC. "We're using extraordinary tools because there is extraordinary circumstances that dictate those."

Acting Homeland Security Secretary Kevin McAleenan also defended the use of tariffs to deter illegal immigration on Sunday, appearing on CNN's "State of the Union."

"I think what the president said, what the White House has made clear is we need a vast reduction in the numbers crossing," McAleenan said.

He listed various benchmarks where the U.S and Mexico can work together to decrease the flow of illegal immigration, including "going after" those transporting migrants and profiting, and "partnering and coordinating on asylum and how we treat people that actually need protections coming from Central America."

McAleenan also called movements into the U.S. from Mexico "overt" on Sunday and said the U.S. needs Mexico to do more to counter the flow.

"These crossings into Mexico are happening on a 150-mile stretch of their southern border," he said. "This is a controllable area. We need them to put their authorities down there and interdict these folks before they make this route all the way to the U.S."

Mulvaney also elaborated Sunday on what else the Mexican government can do to secure the border, including cracking down on the flow of migrants from other countries in Central America, and on domestic terror organizations.

"That border along the southern Mexico needs to be secured," he said. "It is much easier to secure that border than it is our border because it is so much shorter. It is about quarter of the length."

Mexico’s border with the United States is approximately 1,950 miles in length. It has two southern borders, with Belize and Guatemala, that add up to about 700 miles.