US Vice President Joe Biden said on Wednesday that al Qaeda was moving in the direction of smaller but "devastatingly frightening" attacks and he viewed the chance of another Sept. 11-style mass assault as unlikely.
In an interview with CNN's Larry King Live program, Biden also said the situation in Pakistan worried him more than that of Iraq, Iran and Afghanistan.
"It's a big country," Biden said of Pakistan. "It has nuclear weapons that are able to be deployed. It has a real significant minority of radicalized population. It is not a completely functional democracy in the sense we think about it. And so ... that's my greatest concern."
Biden, who was the chairman or ranking member on the Senate Foreign Relations Committee in the decade before becoming vice president, said Iran's nuclear program was a "real concern."
"If they continue on the path of nuclear weapons and were able to gain even a modicum of the capability, then I worry what that does ... what pressure that puts on Saudi Arabia, on Egypt, on Turkey. ... To acquire nuclear weapons, that's very destabilizing," he said.
Although US intelligence chiefs testified before a congressional panel recently that new al Qaeda-backed attacks are certain in the coming months, Biden said he thought any attempt would be small-scale.
"The idea of there being a massive attack in the United States like 9/11 is unlikely, in my view," he said, referring to the Sept. 11, 2001, hijacked plane attacks on New York and Washington, which left nearly 3,000 dead.
"If you see what's happening, particularly with al Qaeda and the Arabian Peninsula, they have decided to move in the direction of much more small bore but devastatingly frightening attacks," Biden said.
He said a likely model was the attempted Christmas attack on an airliner headed for Detroit. Umar Farouk Abdulmutallab, 23, is accused of trying to blow up the Amsterdam-to-Detroit flight with a bomb sewn into his underwear.
"The concern relates to somebody like a shoe bomber or the underpants bomber, the Christmas attack or someone just strapping a backpack on them with weapons ... and blowing up," Biden said.
Asked if an attack like that would actually happen, he said, "Well, I think there are going to be attempts."
The vice president expressed optimism about Iraq, saying it could end up being "one of the great achievements of this administration."
"You're going to see 90,000 American troops come marching home by the end of the summer," Biden said. "You're going to see a stable government in Iraq that is actually moving toward a representative government."
He said he had visited Iraq 17 times, going every two or three months.
"It has impressed me," Biden said. "I've been impressed how they have been deciding to use the political process rather than guns to settle their differences."