New York City Mayor Bill de Blasio defended a program to provide undocumented immigrants with municipal identification cards, saying the IDs would not make it easier for terrorists to infiltrate the U.S.

“The leading experts anywhere in the country in terms of the local security force on fighting terrorism, the leading authority is the New York City Police Department,” he told Fusion’s Jorge Ramos Thursday. “We have a thousand officers devoted to anti-terrorism efforts we have officers all around the world. NYPD obviously understands terrorism from the perspective of the cities in the United States. It’s borne the brunt of the problem. This effort was done with the NYPD

Undocumented immigrants cannot apply for a driver’s license in New York State, and the IDs would help the estimated 500,000 undocumented immigrants who live in the city gain access to government services, such as public school and libraries.

The New York City Council approved the identification card program in June with the backing of an overwhelming majority. In recent days, however, de Blasio’s counter-terrorism strategy has come under scrutiny. John Lehman, a former member of the 9/11 Commission, called out the mayor for inadequately preparing for an attack by the Islamic State in Iraq and Syria (ISIS). Among other charges, Lehman disparaged the ID program from not adhering to the federal standards of the REAL ID program.

“You need a reliable way of identifying people. You don’t simply issue ID cards willy nilly to anybody who wants them and shows up and has his picture taken and tells you what his name is,” he told The Hill.

Ramos asked de Blasio whether he was concerned about the possibility of a terrorist attack on New York.

“Of course, of course,” he said. “We’ve just in the last few days seen ISIS give very clear instructions to their followers to look at targets in the United States.”

He continued: “We are the number one terror target in the United States already. And I’ve said very clear, that’s a constant, it’s not going to change anytime soon.”