Another man said bluntly: "Please forgive me, but I would like to say we've been fighting your war."

But she was also on an offensive of her own, coiled with pent-up frustration about Pakistan's incremental handling of terrorists. The sentiment was quickly echoed by other US officials, including on Friday in Washington by White House spokesman Robert Gibbs.

As she sparred with Pakistani citizens and journalists, Clinton faced sharp questions about the secret US program that uses unmanned aircraft to launch missiles to kill terrorists along the porous, ungoverned border with Afghanistan.

But she refused to go into detail about the classified strikes that have killed both key terror leaders and bystanders, long a source of outrage among Pakistan's population despite an equally deadly campaign of militant-spawned bombings.

Before flying Friday to the United Arab Emirates for consultations with Palestinian leaders on Mideast peace prospects, Clinton appeared to slightly temper her earlier comments that some Pakistani officials knew where al-Qaida's upper echelon has been hiding and had done little to target them.

"We don't know where, and I have no information that they know where, but this is a big government. You know, it's a government on many levels. Somebody, somewhere in Pakistan must know where these people are. And we'd like to know because we view them as really at the core of the terrorist threat that threatens Pakistan, threatens Afghanistan, threatens us, threatens people all over the world," Clinton said.

A day earlier she had been more explicit in her skepticism, telling a Pakistani journalist in Lahore: "I find it hard to believe that nobody in your government knows where they are and couldn't get them if they really wanted to. Maybe that's the case. Maybe they're not gettable. I don't know."

A top Pakistan official insisted Friday that his country is fighting back against militants. "We have decided to fight back," said Interior Minister Rehman Malik, who joined Clinton at a police training center.