ISLAMABAD, Pakistan — Threats of U.S. military action inside Pakistan to counter al-Qaida militants have highlighted the shaky relationship between these two key players in the war on terror.

President Bush said this week that he would "absolutely" order military operations inside Pakistan if Osama bin Laden or other top terrorists were found to be hiding here.

Pakistan's leader, Gen. Pervez Musharraf, also said the United States had threatened to blow his Islamic nation "back to the Stone Age" if he didn't switch his support from Afghanistan's pro-al-Qaida Taliban regime to the American-led war on terror following the Sept. 11, 2001 attacks.

"These comments only expose how tenuous and fragile Pakistan's relationship is with the United States," Pakistani analyst and retired army general Talat Masood said today. "They prove a lot more has to be done to establish a relationship on a much more solid foundation."

Bush, who meets Musharraf today at the White House, has repeatedly praised Pakistan for arresting hundreds of al-Qaida operatives inside this South Asian nation, the world's second-biggest Islamic country with a population of 160 million.

But the United States has also said Pakistan can do more to prevent militants crossing from its tribal regions into Afghanistan, where Taliban-fanned violence has reached its deadliest proportions since the American-led invasion that toppled the hard-line regime.

On Thursday, Pakistan's government vowed to not let foreign forces enter its territory, a day after Bush told CNN he would order American military action inside the Islamic nation if actionable intelligence surfaced that bin Laden was hiding here.

Bin Laden's whereabouts are unknown, but he is believed to be hiding along the porous Pakistani-Afghan frontier, where about 100,000 Pakistani, U.S. and Afghan forces are hunting Taliban and al-Qaida militants.