By Jonathan Landay
WASHINGTON (Reuters) - U.S. President Donald Trump on Saturday predicted Mexico would strongly enforce a new deal under which it agreed to expand a controversial asylum programme and boost security on its southern border to stem Central American migrants trying to reach the United States.
The deal, announced on Friday after three days of negotiations in Washington, averted Trump's threatened imposition of 5% import tariffs on all Mexican goods starting on Monday.
"Mexico will try very hard, and if they do that, this will be a very successful agreement between the United States and Mexico," Trump wrote in a tweet on Saturday morning.
Trump also said Mexico would immediately begin buying "large quantities" of agricultural goods from U.S. farmers, who have been hit hard by his trade war with China and risked a new blow from Mexican retaliation if Trump had imposed tariffs.
It was not immediately clear, however, whether Mexico made such a pledge. There was no mention of expanded Mexican purchases of U.S. agricultural products in the joint U.S.-Mexican declaration outlining the immigration deal.
The White House did not immediately respond to a request for comment.
Trump, a Republican, has made stemming illegal immigration a signature issue of his presidency. He has been frustrated by a surge through Mexico of Central American migrants seeking asylum in the United States.
Under the new deal, Mexico agreed to the immediate expansion along the entire border of a programme under which the United States returns asylum-seeking migrants to Mexico to await adjudication of their cases.
The programme - commonly known as Remain in Mexico - has been operating since January in the border cities of Tijuana, Mexicali and Ciudad Juarez.
The American Civil Liberties Union and other rights groups are pursuing a legal challenge to the programme, which has returned to Mexico more than 10,390 people, mostly Central Americans.
Mexico also agreed to take stronger measures to stem illegal immigration to the United States, including deploying militarised National Guard forces on its southern border beginning on Monday.
U.S. border officers detained more than 132,000 people crossing from Mexico in May, the highest level since 2006. Trump threatened to keep raising import duties on Mexican goods up to 25% unless Mexico acted to stem what he has called an "invasion."
But the threat angered business groups and even some Republican allies, who warned that a trade fight with Mexico would hurt the U.S. economy and lobbied Trump's administration to back down.
The deal announced on Friday did not include a U.S. demand that Mexico accept a "safe third country" designation that would have forced it to permanently take in most Central American asylum seekers.
(Reporting by Jonathan Landay in Washington; Additional reporting by Jan Pytalski in Washington; Editing by Matthew Lewis)