(AP) New York City has entered a "new era" of potential terror threats as hostilities between the United States and extremists from the Islamic State group intensify, Police Commissioner William Bratton said Tuesday.

Bratton told reporters that there is no current information pointing to a specific threat against the city. But he said that the New York Police Department continues to worry that American citizens who have joined forces with the Islamic State group in Syria and Iraq could return home to New York to commit acts of terror.

"This is a new world -- the evolving world of terrorism -- and we are staying ahead of it," Bratton said. "We have been focused on it, and I believe we are as prepared as any entity can be to deal with the threats. But the reality is that we are living in a new era of potential terrorism."

Bratton also said that the Islamic State organization has demonstrated a sophisticated command of how to use the Internet to cultivate sympathizers in the West.

"We are quite concerned, as you would expect, with the capabilities of ISIS, much more than al-Qaida ever was able, to project their ability to use social media to try and spread their recruitment efforts and try to inspire," Bratton said, using an acronym for the group.