WASHINGTON (CBSNewYork) — CIA Director John Brennan has been warning this week that despite battlefield losses, ISIS remains formidable and has a large cadre of fighters who could attack in the West.

As CBS2 Political reporter Marcia Kramer reported, Brennan’s words were both sobering and scary as he spoke before the Senate Intelligence Committee on Thursday. He said ISIS has a two-pronged strategy for spreading havoc in the west – training its own fighters and inspiring others to mount terror attacks.

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Brennan said ISIS already has a lot of western fighters at the ready.

“ISIL has a large cadre of Western fighters who could potentially serve as operatives for attacks in the West,” Brennan said, using another acronym for the group, “and the group is probably exploring a variety of means for infiltrating operatives into the West, including refugee flows, smuggling routes, and legitimate methods of travel.”

It was a frank and terrifying assessment of the terror capabilities of the Islamic State. Brennan told the committee that despite intense efforts by the United States and other nations, while the number of ISIS fighters has been reduced, it is still greater than the number of al-Qaeda fighters.

The group claims 18,000 to 22,000 in Syria and Iraq down from 33,000, along with 5,000 to 8,000 in Libya, possibly more than 1,000 in Egypt, and hundreds more in Afghanistan, Pakistan, Yemen, and Nigeria.

Brennan said ISIS is gradually cultivating its various branches into an interconnected network. The branch in Libya is likely the most advanced and most dangerous, but ISIS is trying to increase its influence in Africa, he said. The ISIS branch in the Sinai has become the “most active and capable terrorist group in Egypt,” attacking the Egyptian military and government targets in addition to foreigners and tourists, such as the downing of a Russian passenger jet last October.

Other branches have struggled to gain traction, he said. “The Yemen branch, for instance, has been riven with factionalism. And the Afghanistan-Pakistan branch has struggled to maintain its cohesion, in part because of competition with the Taliban.”

Brennan went on to note that in the wake of attacks in Orlando, San Bernardino and elsewhere, “ISIL is attempting to inspire attacks by sympathizers who have no direct links to their group.”

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Authorities said Omar Mateen pledged allegiance to ISIS on Facebook and in phone calls to 911 while he gunned down 49 people at the gay nightclub Pulse early Sunday morning.

Brennan called ISIS a “formidable adversary,” but said the U.S.-led coalition has made progress combating the group, which has had to surrender large swaths of territory in Iraq and Syria and has lost some of its leaders in airstrikes. ISIS has struggled to replenish its ranks of fighters, Brennan said, because fewer of them are traveling to Syria and others have defected.

“The group appears to be a long way from realizing the vision that Abu Bakr al-Baghdadi laid out when he declared the caliphate two years ago in Mosul,” Iraq, Brennan said.

U.S. Sen. Richard Burr (R-N.C.), chairman of the Senate Intelligence Committee, insisted the nation has more to do to eradicate ISIS.

“We must attack them where they raise money; where they plan; where they recruit, and we must deny them a safe haven,” Burr said.

Terror expert Manny Gomez said that in the United States – especially in New York, which is a top terror target – the primary threat is from home-grown lone-wolf attackers who are radicalized and inspired by ISIS. To find such people, Gomez said, the FBI needs greater investigative authority.

“The FBI has numerous incredibly sophisticated techniques they could use, but they could only use these techniques if the Attorney General guidelines – ultimately, the law – lets them,” Gomez said. “We need to take the cuffs off of them to let them conduct a more meaningful investigation.”

Gomez said the FBI needs to be able to keep cases open longer, and to have greater authority to use various surveillance techniques.

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