Story highlights U.S. commander wants an investigation complete before Christmas

Pakistan denies firing first at a NATO aircraft that killed two dozen Pakistanis

The Pakistani Taliban say Pakistan must respond in kind to the attack

A top Afghan official warns of possible conflict with Pakistan

Tensions among Pakistan, Afghanistan and the United States jumped a notch Monday, with Pakistan's prime minister warning there would be "no more business as usual" with Washington after NATO aircraft killed two dozen Pakistan troops.

Pakistani Prime Minister Yousuf Raza Gilani told CNN in an exclusive interview that Pakistan is re-evaluating its relationship with the United States in light of the airstrike, which NATO called a "tragic unintended" event. He said the South Asian nation wants to maintain its relationship with the United States so long as there is mutual respect and respect for Pakistani sovereignty.

Asked directly if Pakistan is getting that respect, Gilani said: "At the moment not."

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"If I can't protect the sovereignty of my country, how can we say that this is mutual respect and mutual interest?" he asked.

The Pakistani Taliban urged Pakistan to respond in kind to the airstrike, while a top adviser to Afghan President Hamid Karzai warned that Afghanistan and Pakistan could be on a path to conflict.

In his CNN interview, Gilani highlighted incidents such as the killing of the Pakistani troops and a U.S. raid into Pakistan to kill Osama bin Laden as violations of his country's sovereignty.

"You cannot win any war without the support of the masses ... and such sort of incidents makes people move away from this situation," he said.

Pakistan is a vital land supply route into Afghanistan for the United States and its allies, and a key partner in the battle against al Qaeda and its aligned jihadist movements. But Pakistani authorities turned back 300 trucks carrying NATO supplies and fuel into Afghanistan on Monday, and the prime minister said his government had not yet decided whether to boycott an upcoming Bonn conference on the future of Afghanistan.

Details of Saturday's deadly raid remained unclear Monday, and the chief of U.S. forces in the region named an Air Force general from the military's Special Operations Command to lead an investigation. Gen. James Mattis ordered the investigating officer, Brig. Gen. Stephen Clark, to report back to him by December 23.

According to two senior U.S. officials with direct knowledge of initial reporting on the incident, the probe is focusing on what coordination failures occurred before the airstrike.

One of the officials said initial reports indicate U.S. and Afghan forces said shots were fired across the border from Pakistan, noting that it is a known tactic of insurgents to fire into Afghanistan from very close to Pakistan border checkpoints because they believe it will give them sanctuary. The United States believes the Pakistanis "were called" before NATO opened fire, the official said, but he added that "at this point, we just don't know exactly what coordination was done."

A NATO official said Afghan troops were working with elements of U.S. Special Operations forces in a combined mission on the Afghan side of the border.

Pakistani military spokesman Maj. Gen. Athar Abbas denied the reports that Pakistani troops had prompted the attack Saturday by firing on the NATO helicopters. Speaking by phone to Pakistan's Geo TV News, Abbas said NATO helicopters fired first on the Pakistani military checkpoints.

Abbas said the soldiers notified Pakistani military headquarters, which informed NATO authorities immediately. The spokesman said Pakistani soldiers fired at the NATO aircraft in retaliation.

Speaking in London, the chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey, acknowledged that the U.S.-Pakistani relationship was "troubled." But he suggested it would survive once the two nations work through the "real tragedy" of the Pakistani deaths.

"We've had other moments before," Dempsey said. "I'm hopeful that with the relationships we've built leader-to-leader and worked at over the past years, that we can find our way forward. But I understand the anger. I understand the concern."

The White House offered its condolences to Pakistan, while State Department spokesman Mark Toner said Washington was concerned about the impact the incident could have on relations with Pakistan.

"The relationship is vitally important to both countries. We both face a shared threat from extremists. ... We're taking this very seriously," he said.

A U.S. official who spoke on condition of anonymity told CNN that Pakistan remains a "critical" partner in counterterrorism, "and we do not anticipate significant changes in that relationship."

The Pakistani Taliban appeared to try to widen the rift Monday. A spokesman for the fundamentalist Islamic movement, Ihsanullah Ihsan, said in a phone call to CNN that the U.S. will infringe on Pakistan's sovereignty and continue operations on Pakistani soil in the coming days.

Ihsan said Pakistan must respond in kind to the NATO attacks, and he warned that the Pakistani Taliban will continue jihad as long as Pakistan remains an ally of the United States.

In Kabul, meanwhile, a senior adviser to President Karzai said Afghanistan and Pakistan may be on a course toward military conflict.

Ashraf Ghani said the link between Pakistan and the assassination of a former Afghan president had united his country "against interference."

Ghani accused Pakistan of harboring and assisting the insurgency in Afghanistan, and said his country's neighbor probably helped the suicide bomber who killed former Afghan President Burhanudin Rabbani in September.

"The assassination of President Rabbani has gelled the nation together against interference. And one or two more actions could put us in an irreversible course (toward) conflict. And we've shown through our history that we are a match for any invader," he said.

The two nations have been trading accusations in the border regions in the past few months, with Pakistan accusing the Afghans of harboring militants and Afghanistan claiming Pakistani shells have hit Afghan territory.

But on Sunday, a spokesman for Karzai urged Pakistan to come to the Bonn conference, which is being billed as a chance to start a reconciliation process in Afghanistan.

"We want Pakistan to participate in that. We want Pakistan to be part of the solution in Afghanistan," Aimal Faizi said.