NEW YORK (AP) — At a recent briefing in lower Manhattan, the New York Police Department gave an auditorium full of private security executives plenty to worry about.

One of the NYPD’s intelligence analysts warned that New Yorkers have gone to fight in the Syrian civil war and could come back radicalized against the West. A high-ranking officer described drills testing the NYPD’s ability to respond to a dirty bomb attack. And a detective offered a detailed analysis of the deadly siege at a shopping mall in Nairobi, brashly challenging the Kenyan government’s claim that the gunmen were dead.