House Homeland Security Chair Rep. Michael McCaul said today he believes that ISIS, the jihadist army that has taken control of large part of Iraq and brutally murdered American journalist James Foley, has external operations under way to hit the West.

"Their focus right now is establishing the caliphate. But don't kid yourself for a second, they [are] intent on hitting the West. And there are external operations, I believe, under way," McCaul, R-Texas, told ABC's George Stephanopoulos on "This Week."

"We have tens of thousands of foreign fighters from all over the world pouring into this safe haven that's now been established, including hundreds of Americans with Western passports and legal travel documents, which would enable them not only to travel to Western Europe, but to the United States," McCaul added.

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Also on "This Week", retired Gen. John Allen - who has called ISIS a clear and present danger - said that destroying the group would require "a comprehensive approach" that would necessitate more resources.

"It's going to take more than what we're doing right now, George. There's just no question of this," Allen said on "This Week." "We need to give the American public more clarity in terms of our commitment solely using the terms boots on the ground.

"I think we've been very clear that we don't want to put American maneuver forces necessarily, conventional maneuver forces back on the ground, but we have really significant capabilities to provide special operators into these formations, both at the tribal level, some of the more recently emerging Sunni conventional forces that are appearing in northwest Iraq, the Free Syrian Army, and Sunni tribes in Syria," Allen added.

Allen also told Stephanopoulos that the effort to eliminate ISIS might mean working toward the same goal as the regimes in Iran and Syria, even if the efforts were not coordinated.

"I think that the actions that we take may, in fact, be not in coordination, necessarily, but provide an opportunity for a coordinated effort," he said.

"But we don't share any values with the Iranian regime, and we don't share any values with the Syrian regime," Allen added. "The Syrians, in fact, are one of the principle reasons that ISIS has had the opportunity to incubate to this point to the level that it is, to the threat that it has become. The Assad regime, in fact, has turned a blind eye to the development of ISIS and permitted ISIS ultimately to attack that element that we have been and ought to be supporting in Syria, the free Syrian movement."

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