Last month, Mayor Bill de Blasio joined mayors from across the country in Tornillo, Texas. He was hoping to get inside a facility holding migrant children separated from their parents at the southern border.

"Even in this moment of crisis, there are some seeds of hope here," de Blasio on June 21.

De Blasio was not allowed inside the tent city, so he crossed the border and entered Mexico. He says he was trying to get a better view of the center. But the Trump administration says that border crossing was illegal.

U.S. Customs and Border Protection fired off a letter to the NYPD about the crossing, saying it violated the law. The city police department confirms it received the letter. The Associated Press first reported on its contents.

"I want to address absolutely ridiculous allegations made this week," the mayor said Wednesday. "At no point did we disregard any instructions from federal authorities. Period. So why suddenly, weeks later, is this letter showing up from the federal government? Well, it is another attempt to distract from an inhumane policy."


The mayor says his security detail spoke to border agents in Texas and that those agents spoke to their supervisor. He says the agents agreed to allow him to cross the U.S. border into Mexico at a checkpoint.

"We came back the exact same way, both times showed passports, went through with the approval of the agents at the entry point," de Blasio said.

De Blasio suggested that the Trump administration's accusation that he broke the law is an attempt to silence him. He's repeatedly denounced the separation of families at the border.

"I won't stand for this policy, and I won't be silent, and I won't accept any effort to intimidate," the mayor said.

A spokesman for the NYPD said the department is not taking any action based on the federal government's letter. U.S. Customs and Border Protection did not respond to a request for comment.