The Islamic State's use of social media to call for lone wolf terror attacks in New York City has raised concerns in the NYPD although there is still no specific threat, Police Commissioner William Bratton said Tuesday.

The militant terrorist group, also known as ISIS and ISIL, is fighting in Syria and Iraq. The group has been more adept than al-Qaida at using message boards to encourage and enable attacks, Bratton told reporters during the dedication of two new police harbor launches in Brooklyn.

"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," Bratton said.

Jewish community leaders are expected to hear similar remarks from Bratton and his intelligence chief John Miller Wednesday morning at a pre-High Holy Day briefing at police headquarters.

A number of terrorist magazines, including Inspire, have put out recipes for car bombs and have listed Times Square as a potential target, he noted. A recent issue of Inspire tried to correct mistakes terrorist Faisal Shahzad made when he concocted a car bomb and tried but failed to detonate it in the Times Square area in May 2010, Bratton said.

Law enforcement officials said Shahzad's device, constructed of fertilizer, gasoline, propane tanks and firecrackers, was placed in a Pathfinder on 45th Street. The device fizzled and smoked, but failed to explode.

Shahzad later told investigators he had received bomb-making instructions in Pakistan and that he planned to cause mass casualties. He is serving a life sentence in federal prison.

About 100 U.S. citizens are believed to have joined the Islamic State in the Mideast and U.S. officials are concerned that some could try and return to use their terror training here, Bratton said.

"This is a new world, the evolving world of terrorism," Bratton said.

But the police commissioner also noted that the NYPD can't ignore the reality of potential threats to the city coming out of the Syrian conflict.

The city's counterterrorism apparatus built up under Bratton's predecessor Ray Kelly was expanded Tuesday with the addition of two new police vessels, Bratton said. The 62-foot launches are equipped with sonar, radiation detection and underwater camera systems.

The vessels were named after police officer Harry Ryman, who was killed in the line of duty in August 1980, and officer Joseph McCormack, who was killed while off duty by a emotionally disturbed man in September 1983.