The Trump administration indicated Monday that a deal it struck with Mexico in June to limit immigration in exchange for forgoing 5% tariffs on Mexican goods was holding up, signaling that it was unlikely to follow through with the levies.

President Trump threatened in May to place a 5% tariff on all goods imported from Mexico if it did not take steps to limit immigration into the United States. At the time, immigrants from countries like Guatemala had been passing through Mexico in high numbers on their way to the U.S.

Mark Morgan, the acting commissioner of U.S. Customs and Border Protection, said Monday that detentions and turnaways at the U.S.-Mexican border were down, an indication that fewer immigrants were making the effort to reach the U.S. Morgan pointed to the numbers as proof that the June deal was working.

"The Northern Triangle countries especially, along with the government of Mexico, have really joined the United States as true partners for the first time," Morgan said. "They really are seeing this as a true regional crisis that needs continuing coordination cooperation and effort. That this is not just a United States problem, that this is a regional crisis that needs regional support and regional solutions."

The deal involved Mexico deploying its national guard to its southern border and take other unspecified actions to dismantle human smuggling and trafficking organizations. If there hadn't been sufficient progress within 90 days — the deal did not indicate how that would be determined — Mexico would be obligated to pursue an "ongoing regional strategy" that would involve the governments of El Salvador, Guatemala, and Honduras. Otherwise the U.S. could return to imposing the tariffs.

Morgan said 64,000 people were detained or turned back at the southwest border in August. That was down 22% from the previous month and 56% below May, the most recent high point in immigration. He said the decline was a result of cooperation between the governments of the U.S., Mexico, and the Central American countries.

The comments come the day before Mexican officials, led by Foreign Affairs Secretary Marcelo Ebrard, are set to meet with their Trump administration counterparts in Washington, D.C. to discuss progress relating to the summer deal to avoid tariffs. The Tuesday meeting between U.S. and Mexican officials is meant to evaluate the progress over the 90-day window.