The number of arrests along America’s southern border dropped 28% in June from the previous month, the first monthly decline this year, the Department of Homeland Security announced on Tuesday. DHS linked the drop to the Trump administration’s hard-line immigration policies and renewed support from the Mexican government to curb people trying to enter the U.S. Border officials have been operating under President Donald Trump’s new “Remain in Mexico” policy, which allows the federal government to force many asylum seekers back across the border while they wait for their applications to be processed. Applicants had previously been allowed to wait in the U.S. “These initiatives are making an impact,” Acting DHS Secretary Kevin McAleenan said in a statement. The number of border crossings typically decreases in summer, the hottest months of the year, but June’s decline was much larger than usual, according to The Washington Post.

The Washington Post via Getty Images DMigrants are gathered inside the fence of a makeshift detention center in El Paso, Texas on Wed. March 27, 2019. (Photo by Sergio Flores for The Washington Post via Getty Images)

McAleenan noted 688,375 people have been apprehended this year, a 140% increase over 2018, and he issued a stark warning about border agents’ capacity to deal with the “full-blown emergency.” There were still more than 100,000 arrests in June, the fourth month in a row with that many detentions, and DHS has been stretched to the limit attempting to stem the flow of people across the border. “We are still in an ongoing border security and humanitarian crisis,” McAleenan said. “Our June apprehension numbers are still higher than last year’s, when we were already in a crisis. We are past the breaking point and in a full-blown emergency. This situation should not be acceptable to any of us.” Trump has made immigration a signature policy of his presidency, replacing any officials he deems unsuited to carrying out his hard-line agenda on the border. He has dismissed reports of inhuman conditions at U.S. detention centers, writing on Twitter that if migrants were unhappy, “just tell them not to come.”

If Illegal Immigrants are unhappy with the conditions in the quickly built or refitted detentions centers, just tell them not to come. All problems solved! — Donald J. Trump (@realDonaldTrump) July 3, 2019