President Trump continued to insist on Monday that the tariff-averting border deal he reached with Mexico on Friday is more robust than critics and news reports suggest, tweeting: "We have fully signed and documented another very important part of the Immigration and security deal with Mexico, one that the U.S. has been asking about getting for many years. It will be revealed in the not too distant future and will need a vote by Mexico's legislative body!"

In a news conference in Mexico City on Monday, Mexican Foreign Minister Marcelo Ebrard said Mexico had not agreed to any secret immigration deal, also denying an earlier tweet in which Trump said Mexico had agreed to buy more U.S. agricultural goods.

Instead, Ebrard said, Mexico agreed that if the flow of migrants to the U.S. did not drop significantly in coming months, both sides would meet again to discuss more aggressive changes to regional asylum rules. "Let's have a deadline to see if what we have works, and if not, then we will sit down and look at the measures you propose and those that we propose," he said. U.S. officials tell The New York Times that Trump's tweet appeared to refer to an agreement in the published deal to revisit the migration situation with Mexico in 45 and 90 days.

In last week's negotiations, the U.S. team had pressed Mexico to enact a "safe third country" system in which migrants fleeing Central America would have to apply for asylum in Mexico, and the U.S. could turn away those who didn't. Mexico refused. "There appeared to be a significant disagreement on Monday between the Mexican government and American officials about what the negotiators actually agreed to regarding further action and the possibility of implementing a 'safe third country' arrangement," the Times reports. U.S. officials said Mexico all but agreed to a regional system that would mimic a "safe third country" law, while Ebrard said the deal effectively put off that discussion. Peter Weber