WASHINGTON - Pakistan already has paid dearly for its failure to know or acknowledge that Osama bin Laden was hiding for more than five years in a compound a short distance from a Pakistani military facility, Pentagon leaders insisted Wednesday.

Pushing back against angry public and congressional accusations that Pakistani officials were complicit in bin Laden's sanctuary there, Defense Secretary Robert Gates said he has seen proof that leaders there were unaware of bin Laden's whereabouts.

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"I have seen no evidence at all that the senior leadership knew. In fact, I've seen some evidence to the contrary," Gates told reporters at the Pentagon. "We have no evidence yet with respect to anybody else. My supposition is, somebody knew."

He would not say who knew but suggested it could have been retired or low-level Pakistani officials.

The Obama administration is reassessing its fragile and sometimes hostile relationship with Pakistan after the bin Laden killing, which may change the stakes for both sides. For the US, it may provide greater leverage in its argument to prod Pakistan to go after the militants that target the US, instead of only those that target Pakistan.

"If I were in Pakistani shoes, I would say I've already paid a price. I've been humiliated. I've been shown that the Americans can come in here and do this with impunity," said Gates. "I think we have to recognize that they see a cost in that and a price that has been paid."

That argument, however, may hold no sway in Congress, which has seen more than $10 billion in aid go to Pakistan over the past 10 years.

If a US aid package to Pakistan should come up for a vote in at least one Senate Appropriations subcommittee, "it would not pass at all. I don't know how I would vote on the issue," said Democratic Sen. Patrick Leahy, chairman of the Appropriations subcommittee that oversees foreign aid.

Gates and Mullen said the Pakistanis are well aware of the swelling frustration in Washington. And they have heard the demands that Islamabad pay a price for its inability or unwillingness to target more aggressively insurgents that are planning and waging attacks against US and coalition troops across the border in Afghanistan.

"I don't think we should underestimate the humbling experience that this (has been) and in fact the internal soul searching that's going on" inside Pakistan's military, said Mullen.

Mullen has forged a close relationship with his Pakistani counterparts, encouraging them to move against high-level terrorists known to be hiding in Pakistan, including al-Qaida's No. 2 leader, Ayman al-Zawahri, and kingpins of the Afghan insurgency such as Mullah Omar and Siraj Haqqani.

Pakistan's continued support is critical for the continued passage of supplies into Afghanistan, as well as its sporadic military operations in some of the insurgent strongholds such as South Waziristan and the Swat Valley.

Mullen said the United States must continue to work with and provide aid to Pakistan. But amid rising anger and distrust of Pakistan across America and in Congress, both men acknowledged that Islamabad must take concrete action to eliminate the havens where militants are hiding along the border with Afghanistan.

Sen. John McCain, the top Republican on the Armed Services Committee, said as lawmakers are under pressure to cut all US spending, he suggested establishing a "set of benchmarks" for Pakistan to meet, such as going after the Haqqani network, border security and focusing on North Waziristan.

While he cautioned against a rush to cut aid to Pakistan, he noted that the US set similar types of benchmarks as it prepared to withdraw troops from Iraq.

In other comments, both Gates and Mullen complained that too much information has been disclosed about the raid by the elite US SEAL team that stormed the compound in Abbottabad and killed bin Laden and four others.

"We are close to jeopardizing this precious capability that we have, and we can't afford to do that," said Mullen. "This fight isn't over."

He and Gates said that former and current US officials have spilled too many details of the operation, risking the security of the special operations forces involved and their families. "It's time to stop talking," he said.