The NYPD faces an unprecedented security challenge with the pope coming later this month, and the United Nations assembling at the same time, said John Miller, deputy commissioners of intelligence and counterterrorism for the NYPD.

Miller said crowd management becomes very complicated, balancing security with the main purpose of the event: that people want to see Pope Francis. His Holiness will be in the city on Sept. 24-25, and the United Nations General Assembly will overlap with his visit.

With the pope's visit, "the NYPD faces one of the most significantly challenging security environments maybe in the history of major policing," Miller said. "It is really something that is multilayered on a level that we've never seen before. And this organization has planned and executed some of the most complicated visits, large events, and historic gatherings of any."

Miller said there will be abo1ut 2,500 officers, plus about another 1,000 people from the intelligence and counterterrorism bureaus.

Police Commissioner Bill Bratton said the NYPD will collaborate with the police departments in Washington, D.C. and Philadelphia, the other cities Pope Francis is visiting.

"The public that's coming to see the pope, those that are coming for the U.N. should feel very comfortable that, as always, we will ensure a safe event ... and certainly in the visit of the pope, a celebratory event for those who want to see him," Bratton said.

Miller said this is considered a National Special Security Event, which makes the secret service the lead organization. But the NYPD will provide the most personnel, including everything from security to traffic management.