Mexico announced it would implement "strong measures" to slow the flow of migrants across its territory towards the southern US border, including the deployment of thousands of Mexican national guard troops. It also agreed to expand a programme 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."
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. "They might have accelerated the timetable, but by and large the President achieved nothing except to jeopardise the most important trading relationship that the United States of America has."
During an interview on CNN, Senator Bernie Sanders 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 honour 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.
Senator Ron Johnson, chairman of the Senate Homeland Security and Government Affairs Committee, had voiced anxiety about the tariffs before the deal was reached. Today, 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. "He's using tariffs as leverage in trade negotiations, and I think he used them as leverage in this situation brilliantly, quite honestly."
Top congressional Democrats yesterday 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 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 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.
