NYPD: Threat to U.S. "growing exponentially" with ISIS

New York Police Department officials assessed the threat that Islamic extremists pose to the United States on the 13th anniversary of the Sept. 11, 2001, terrorist attacks.

"We are safe; however the threat is growing exponentially since the emergence of ISIS," New York Police Commissioner Bill Bratton said on "CBS This Morning" Thursday, referring to the group known as the Islamic State of Iraq and Syria, or ISIS. "As reflected in the president's speech last night, it's something we've been talking about for quite some time, and it is real, and it is growing."

ISIS, also known as the Islamic State of Iraq and the Levant, or ISIL, and al Qaeda are different ideologically. According to Bratton, ISIS is a sophisticated operation that focuses on recruitment and steady growth rather than large-scale acts of terror.

"Al Qaeda was always looking for the big events," Bratton said. "Its history has always been the 9/11 style, the plane bombing, etc. ISIS would be much more into the inspiration of the lone wolf. ISIS would be much more into the solo actor. They're very sophisticated in their capabilities through their videos, through their social media, through their magazines. They're a very sophisticated operation seeking to recruit, more so even than al Qaeda was over the years."

On Wednesday night, the president stated that America "will degrade and destroy ISIS," primarily through airstrikes. NYPD Deputy Commissioner for Intelligence John Miller said that while airstrikes are effective, this group may be larger and more complex than many people would believe.

"What you have is, as the commissioner said, a very sophisticated group made up of former Iraqi generals, strategists, intelligence officials from the Saddam Hussein era," Miller said. "So these are people who have military training, military experience but, more important, organizational experience."

Bratton said the number of ISIS-affiliated Westerners is in the hundreds.

"It's been publicly reported that there are an excess of about 100 Americans, at least 100 Americans," he said. "The Brits anticipate that they've got several hundred over there. The Australians have hundreds also, so the overall scope is known, and the work now is to identify who they are so you can watch for them as they attempt to come back."

Last month, CBS News senior security contributor Mike Morell, a former deputy director at the CIA, told CBS News he would not be surprised if an ISIS militant walked into a mall and opened fire. On Thursday, Miller said that these types of attacks are already happening worldwide.

"If you go back through the attack in Belgium at the Jewish Museum, you see a foreign fighter who was on the ground fighting for ISIS in Syria who returned home and on the way decided to carry out an attack," said Miller, "and when he was captured at the airport, and they recovered the weapon, it was wrapped in an ISIS flag at that checkpoint.

"You have to look at that case, the man who was arrested coming back from Syria who, when they raided his home in Toulouse, France, had the explosive," said Miller. "You have to look at some of these other cases where they have already returned, either carrying out plans and executing plans. Haven't seen it here, but that's a concern."

Bratton said the NYPD wasn't doing anything differently except for expanding upon its expertise that had been developed since 9/11.

"Our predecessor, Commissioner (Ray) Kelly, had really built a world-class counterterrorism operation here," Bratton said. "We have sought to strengthen and expand our relationships with our federal colleagues over these last eight months that we've been here. We're also expanding our conversations with our foreign colleagues. I was on the phone earlier this week with the head of the Metropolitan Police in London. We're hoping he'll be coming here shortly for the joint terrorism conference here, so this is an international concern."