President Donald Trump speaks Thursday before he departs Shannon Airport in Shannon, Ireland. Credit: Alex Brandon | AP

WASHINGTON — President Donald Trump and his acting Homeland Security secretary on Sunday defended their new agreement with the Mexican government to curb migration at the southern border, striking back at Democratic critics — including accusations that at least some parts of the deal predated Trump’s recent tariff threats.

In a series of morning tweets, Trump said that Mexico “was not being cooperative on the Border” before the deal reached Friday. Now, he said, “I have full confidence, especially after speaking to their President yesterday, that they will be very cooperative and want to get the job properly done.”

He also said he could move to reimpose tariffs if Mexico doesn’t follow through on its promises. Some aspects of the deal, he added, remain to be announced — “one in particular,” he said, “will be announced at the appropriate time.”

Meanwhile, Acting Homeland Security Secretary Kevin McAleenan credited Trump’s tariff threats — which would have placed a 5 percent levy on Mexican goods starting Monday, ratcheting up over several months to as much as 25 percent — with producing a breakthrough.

“The president put a charge in this whole dialogue with Mexico with the tariff threat, brought them to the table,” McAleenan said in a “Fox News Sunday” interview, noting that Mexican Foreign Minister Marcelo Ebrard “arrived within hours” to begin talks.

Mexico announced it would implement “strong measures” to slow the flow of migrants across its territory toward the southern U.S. border, including the deployment of thousands of Mexican national guard troops. It also agreed to expand a program allowing Central American migrants to wait in Mexico while they await the adjudication of their asylum claims.

“People can disagree with the tactics,” McAleenan added. “Mexico came to the table with real proposals. We have an agreement that, if they implement, will be effective.”

On Sunday, two Democratic presidential candidates said Trump had exaggerated what his tariff threats against Mexico had accomplished. They echoed a New York Times report alleging that the Mexican government had already agreed to several terms of the deal before Trump publicly floated the prospect of tariffs.

“These are agreements that Mexico had already made, in some cases months ago,” former congressman Beto O’Rourke said in an interview on ABC’s “This Week.” “They might have accelerated the timetable, but by and large the president achieved nothing except to jeopardize the most important trading relationship that the United States of America has.”

During an interview on CNN’s “State of the Union,” Sen. Bernie Sanders, I-Vermont, also said Trump had repackaged earlier agreements with Mexico to declare success in the trade standoff.

“I think what the world is tired of, and what I am tired of, is a president who consistently goes to war, verbal war, with our allies,” Sanders said, adding that Trump should focus on achieving comprehensive immigration reform. “We need a decent relationship with Mexico. They are our allies, as is the case with Canada. We should not be confronting them every other day.”

Trump, in his tweets, lashed out at the New York Times for suggesting the deal was not entirely new and also pointed out that tariffs could be back on the table if the Mexican government does not honor its end of the deal.

“There is now going to be great cooperation between Mexico & the USA, something that didn’t exist for decades,” he said. “However, if for some unknown reason … there is not, we can always go back to our previous, very profitable, position of Tariffs.”

McAleenan echoed that sentiment, saying the dangling threat of tariffs amounted to “a mechanism to make sure that they do what they promise to do, that there’s an actual result that we see a vast reduction in those [migrant] numbers.”

Republican lawmakers appeared relieved in talk-show appearances Sunday.

Sen. Ron Johnson, R-Wisconsin, chairman of the Senate Homeland Security and Government Affairs Committee, had voiced anxiety about the tariffs before the deal was reached. On Sunday, he had nothing but praise for Trump.

“Republicans understand that tariffs are attacks on American consumers, and we don’t want to see them in place long-term, nor do I believe President Trump does, either,” he said on “Fox News Sunday.” “He’s using tariffs as leverage in trade negotiations, and I think he used them as leverage in this situation brilliantly, quite honestly.”

Sen. Thom Tillis, R-North Carolina, speaking on Fox News Channel’s “Sunday Morning Futures,” defended Trump and urged action on a renegotiated North American free-trade deal.

“Republicans need to provide the president with a lot of leeway,” Tillis said, adding that if lawmakers give Trump some “unorthodox” options for negotiating trade agreements, “then America wins.”

Top congressional Democrats on Saturday delivered dual attacks on the deal, saying that the agreement amounted to less than meets the eye while also arguing that the tariff threat that prompted it was reckless. They called on Trump to begin talks on bipartisan immigration legislation.

Senate Minority Leader Charles Schumer, D-New York, said the deal was “likely to be one of the president’s typical, bogus solutions” to justify retreat from the tariffs, which had prompted a fierce backlash from business interests and many Republicans. He added that the provisions in the agreement were “likely to have only a small impact on solving the root causes of Central American migration because many of the components are things Mexico is already doing.”

House Speaker Nancy Pelosi, D-California, said Trump had “undermined America’s pre-eminent leadership role in the world by recklessly threatening to impose tariffs on our close friend and neighbor to the south.”

“Threats and temper tantrums are no way to negotiate foreign policy,” she said.