The United States pressed a hard case with a difficult ally during an extraordinary two-day diplomatic offensive in Pakistan, arguing on one hand that Pakistan should send its army after militants the U.S. says get special protection from the Pakistani government and on the other that Pakistan should use its influence with Taliban militants to encourage peace in Afghanistan.

Pakistan is unlikely to do either to U.S. satisfaction, leaving a critical counterterrorism partnership on uncertain terms.

U.S. Secretary of State Hillary Rodham Clinton acknowledged Friday that U.S.-Pakistani ties are now badly strained. The U.S. raid that killed Osama bin Laden in Pakistan in May is one reason. The death of two Pakistanis at the hands of a CIA contractor is another.

"Our relationship of late has not been an easy one," Clinton said at the close of meetings centered on U.S. demands for more cooperation. "We have seen distrust harden into resentment and public recrimination. We have seen common interests give way to mutual suspicion. We have seen common interests give way to mutual suspicion."

Leading an unusually large and powerful U.S. delegation, including CIA Director David Petraeus and Joint Chiefs of Staff Chairman Martin Dempsey, Clinton met for four hours of talks with Pakistani officials late Thursday. On Friday, Clinton met alone with Pakistani President President Asif Ali Zardari and Foreign Minister Hina Rabbani Khar, who used a joint news conference to deny that Pakistan shelters or supports a particularly lethal wing of the Taliban, an issue at the heart of the talks with the Americans.

"There is no question of any support by any Pakistani institution to safe havens in Pakistan," for militants of the Taliban-linked Haqqani network, Khar said.

Kahr insisted that Pakistan and the U.S. shared the same goal.

"Pakistan takes the threat of terrorism seriously," she said, noting that thousands of Pakistanis had been killed by extremists over the past decade. "We are committed to this process, we would be willing to do whatever we can to be able to make this a success."

The United States claims the Haqqanis, based in Pakistan's North Waziristan region, are mounting direct assaults on U.S. soldiers and civilians in Afghanistan that justify a stepped-up U.S. military push against them in Afghanistan and more CIA drone strikes to kill clan leaders in Pakistan.

The U.S. has grown increasingly impatient with Pakistan's refusal to take military action against the Haqqani network and its ambivalence, if not hostility, to supporting Afghan attempts to reconcile Taliban fighters into society.

Clinton warned that that stance is no longer acceptable while American officials warned that if Pakistan continued to balk, the U.S. would act unilaterally to end the militant threat. She also confirmed that the U.S. had tried to directly enlist the Haqqanis in peace efforts.

Clinton is the first U.S. official to publicly acknowledge the outreach, which was first reported by The Associated Press in August. She said the meeting was organized by Pakistan's intelligence service and was preliminary "to see if (the Haqqanis) would show up."

The U.S. is asking for more Pakistani pressure on the Haqqanis, which the U.S. military considers the biggest threat to U.S. troops in Afghanistan. That's a tough sell for two reasons: Pakistan's army is already stretched thin by other counterterrorism operations the country's leaders consider a higher priority, and many in Pakistan view groups such as the Haqqanis as disaffected brethren, not enemies. By wide margins, Pakistanis also oppose any U.S. intervention in their country, including the clandestine drone campaign.

U.S. officials have accused Pakistan's military spy agency, Inter-Services Intelligence agency, or ISI, of harboring or helping the Haqqanis, which Pakistan's leaders deny. Clinton pointed to the joint U.S. and Afghan campaign against the militants on the Afghan side of the order and said that Pakistan must do the same. On Thursday, in the Afghan capital, she said those who allow such safe havens to remain would pay "a very big price."

U.S. officials have not been precise in public about what they are asking Pakistan to do militarily, and many privately acknowledge that any large military operation in the rugged tribal areas is unrealistic. Nor is the powerful Pakistani intelligence service likely to cut ties to the Haqqanis.

Clinton herself alluded to the utility of those ties, saying that the more important U.S. request of Pakistan is that it try to pressure Taliban militants to reconcile with the U.S.-backed government in Afghanistan.

She said the military fight against the group must be intensified to persuade members to quit and rejoin society. "We don't know if this will work, but we believe strongly we must try it," she said.

"Pakistan has a critical role to play in supporting Afghan reconciliation and ending the conflict," Clinton said. "We look to Pakistan to take strong steps to deny Afghan insurgents safe havens and to encourage the Taliban to enter negotiations in good faith."

Clinton said the urgency of the situation required that action take place "over the next days and weeks, not months and years," and she warned that many in Congress are fed up and ready to pull back on the billions in aid the U.S. provides to Pakistan.

"We should be able to agree that for too long extremists have been able to operate here in Pakistan and from Pakistani soil," Clinton told reporters at the news conference with Khar. "No one who targets innocent civilians, whether they be Pakistanis, Afghans, Americans or anyone else should be tolerated or protected."

In Washington, Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, had tough words for Pakistan during a speech to the Council on Foreign Relations.

"We have the right to target not only forces and artillery attacking our forces in Afghanistan from across the border in Pakistan, but to target the people controlling those forces as well," he said.

The U.S. and Pakistan remain at odds over the proper sequencing for peace talks with the Taliban and their allies, said a Pakistani security official, who spoke on condition of anonymity to discuss the closed-door talks. Pakistan thinks the U.S. strategy of additional military action will not work, the official said.

Speaking to a group of Pakistani journalists, Clinton said it was unrealistic to think Pakistan's intelligence service did not have connections with insurgents.

"Every intelligence agency has contact with unsavory characters, that is part of the job of being in an intelligence agency," she said. "What we are saying is let's use those contacts to try to bring these people to the table to see whether or not they are going to be cooperative." She noted that it was the Pakistani intelligence services that requested the U.S. meet with the Haqqanis

A senior official traveling with Clinton said the meeting took place over the summer at the request of Pakistani intelligence, but would not give an exact date or the venue for the talks. The official said the Americans had delivered a clear message that "the door is open to those who can meet these red lines" but that those who chose to continue to fight would face intensified attacks. The official spoke on condition of anonymity due to the sensitivity of the matter.

Officials pointed out that after the meeting the Haqqanis attacked a U.S. base in Afghanistan and are believed to be responsible for a strike on the U.S. Embassy in Kabul in September.

Several former and current U.S. and Afghan officials have told the AP that the U.S. met with Ibrahim Haqqani, the brother of the elder Jalauddin Haqqani, who heads the Haqqani network. The U.S. also held several meetings with Taliban leader Mullah Mohammed Omar's former secretary Tayyab Aga. The talks were held in Bahrain and Germany, they said speaking on condition of anonymity because of the sensitivity of the issue.

Washington's outreach to the Taliban has angered both Pakistan and the Afghan government. Talks with Aga ground to a halt earlier this year after they were leaked by officials in President Hamid Karzai's office, infuriated that Washington had opened up its own channels of communication with the Taliban.

___

Gearan reported from Washington. Associated Press writers Sebastian Abbot and Kathy Gannon in Islamabad and Donna Cassata in Washington contributed to this report.