The U.S. should rethink its approach in Pakistan, including a multimillion dollar program aimed at training and equipping tribal militants, unless Islmabad does more to keep terrorists from crossing the Afghan border, a top Democrat said Tuesday.

Sen. Carl Levin, chairman of the Armed Services Committee, told reporters after a three-day trip to the region that U.S. officials have little confidence that pieces of the Pakistan government, particularly its army, are working actively to stop the flow of Taliban fighters and weapons into Afghanistan. In some cases, these groups might even be providing terrorists' support, he said.

"If that's our intelligence assessment, then there's a real question as to whether or not we should be putting money into strengthening the Frontier Corps on the Pakistan side," Levin, D-Mich., said in a conference call from Qatar.

Levin is among a growing chorus of Democrats questioning the more than $10 billion in U.S. military and economic aid given to Pakistan to fight terrorism since the Sept. 11 attacks. Last month, a report by the Government Accountability Office found that despite the money, terrorists are still operating freely along the Afghan border.

The senior Democrat, who oversees a major policy bill authorizing more than $600 billion in annual defense spending, said he is interested in restricting $70 million designated for the Pakistan's Frontier Corps, a paramilitary force operating in the western tribal region.

He stopped short of saying the U.S. should conduct anti-terrorism strikes inside Pakistan without Islmabad's permission, at least for now. Democratic presidential hopeful Barack Obama caused a stir last August when he said the United States should act on intelligence about top terrorist targets in Pakistan even if President Pervez Musharraf refuses. His comments prompted Pakistani officials to warn against U.S. incursions into their country.

"I don't think we ought to be focusing on moving our troops into Pakistan; we ought to be insisting that Pakistan remove those threats," Levin said. "And if they don't remove those threats, that should change our policy, including our military funding for the Pakistanis if they're not going to address the threats that end up hurting and harming our people and endangering Afghanistan."

Since 2001, most of the U.S. aid spent in Pakistan — $5.6 billion — has gone toward reimbursing Pakistan's military for combat operations. About $1.5 billion has paid for military training and equipment, while the rest of the money is devoted to economic aid and other priorities, such as legal reform and local police training.

In recent days, several lawmakers have flown to the region on fact-finding trips while Congress was on Memorial Day recess.

Levin's Democratic colleague, Sen. Russ Feingold of Wisconsin, said in an interview this week that Pakistan should quickly restore dozens of judges ousted by Musharraf. Feingold also said it was important for the United States to engage the country's various political parties to make up for the past mistake of relying solely on Musharraf.