Pakistan has already 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 U.S. public and congressional accusations that Pakistani officials were complicit in Bin Laden's sanctuary there, Defense Secretary Robert Gates said he'd seen proof that leaders there were unaware of Bin Laden's whereabouts.

"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 wouldn't say who but suggested it could have been retired or low-level Pakistani officials.

Adm. Mike Mullen joined in a broad defense of Islamabad's leadership. And he and Gates urged patience as the "humiliated" country worked through the problems emanating from the U.S. clandestine raid deep into Pakistan that killed Bin Laden on May 2.