Pakistan withdrew from an international conference on stabilizing Afghanistan to protest the deadly attack by American forces on its troops, widening a fresh rupture in ties with a nominal ally that is endangering the U.S. plan for gradually ending the war.
In an unusually hostile comment, a top Pakistani army general said Tuesday that the deaths of 24 Pakistani soldiers were the result of a "deliberate act of aggression." He said the military has not decided whether to take part in an American investigation into the weekend encounter along the mountainous Afghan border.
The hard line was aimed partly at pacifying the country's anti-American public, most of whom detest their leaders' close association with Washington. The uncompromising stance of the army was also likely designed to press for more concessions from Washington.
Regardless of motive, Pakistan's retaliatory moves and tough rhetoric lower the chances of greater cooperation in the Afghan war and will make it harder to repair ties with the U.S. once emotions cool.
Those ties have been beset by crises for the most of the year, most notably after the U.S. raid on May 2 that killed Osama bin Laden and wounded Pakistani pride. Each time, U.S. officials have worked to get the relationship back on track, knowing that Pakistan's influence over Afghan Taliban leaders could be key to achieving a negotiated settlement that would allow American combat troops to withdraw from Afghanistan by the end of 2014.
Pakistan needs American aid and diplomatic support but has shown no willingness to listen to American requests to fight insurgents who use the border as a staging area to carry out attacks inside Afghanistan. Indeed, the army is widely believed to support those militants, hoping they can help ensure that any future regime in Kabul shares Pakistan's hostility to India.
Differing versions of Saturday's incident have emerged, but all agree that 24 Pakistan soldiers were killed in attacks on two bases by NATO aircraft. NATO has described the incident as "tragic and unintended," and U.S. officials have expressed their sympathies with the families of the dead.
Hours after the attack, Pakistan closed its two crossings on the western border to trucks delivering fuel, vehicles and food to NATO troops in Afghanistan. A NATO official said military operations could run at the current pace for "several months" because the alliance has stockpiles of supplies and alternative routes into the country.
Islamabad also ordered the U.S. to vacate within 15 days an air base in southwest Pakistan that housed CIA drones which attack militants along the Afghan border. U.S. officials have said this will not greatly impact the drone program because most of the aircraft are flown from bases in Afghanistan.
The decision to skip the Afghan conference Monday in Bonn, Germany, was made during a Pakistani Cabinet meeting.
German Chancellor Angela Merkel said she hoped the government would reconsider.
"They should still understand that the Afghanistan conference is a very important one. It's a very good opportunity to bring forward the political process," she said.
Pentagon press secretary George Little also urged Pakistan to come.
"We believe it's critical that countries in the region and who have interests in Afghanistan attend, and we certainly hope that Pakistan will attend the conference," Little said in Washington.
More than 90 countries are expected to attend the conference, intended to map out a sustainable future for Afghanistan once international troops withdraw. It was once hoped that the conference would help toward reconciliation with the Taliban, but the assassination in September of former Afghan President Burhanuddin Rabbani severely undermined efforts to reach out to the insurgency.
Few had high expectations the conference would result in significant progress. But the absence of Pakistan, the most important country in the peace process, will make even minor achievements more difficult.
Soon after the Pakistani Cabinet meeting ended, two army generals briefed several dozen Pakistani newspaper editors, talk-show hosts and defense analysts on the fallout from the attack.
Maj. Gen. Ashfaq Nadeem, director general of military operations, called the incident a "deliberate act of aggression" and said it was "next to impossible that NATO" did not know it was attacking Pakistani forces, according to people who attended the briefing, which was closed to non-Pakistani media.
In the most detailed account yet of the Pakistani version, he said two or three helicopters attacked the first post, called "Volcano," without warning. Nadeem did not mention whether those soldiers had opened fire on the advancing choppers. Seeing the attack, troops at the nearby "Boulder" post opened fire with anti-aircraft guns. That base was then attacked, he said.
At the Pentagon, Little declined to respond directly to Nadeem's remarks, saying: "No one at this point has the complete narrative on what happened and I think it's important that we wait for the investigation to occur."
U.S. officials said a joint U.S.-Afghan patrol was attacked by the Taliban on the Afghan side of the border in Kunar province. They say while pursuing the Taliban in the poorly marked border area, the patrol seems to have mistaken one of the Pakistani troop outposts for a militant encampment and called in a NATO gunship and attack helicopters to open fire, starting the engagement.
Gen. James Mattis, head of U.S. Central Command, announced Monday he has appointed Brig. Gen. Stephen Clark, an Air Force special operations officer, to lead an investigation and include input from the NATO-led forces as well as the Afghan and Pakistani governments.
But Nadeem said the army may not cooperate with the investigation, saying it had little faith that any U.S. probe will get to the bottom of what happened. He said other joint inquiries into at least two other similar, if less deadly, incidents over the last three years had "come to nothing."
Although Pakistan is angry over the deaths of its soldiers, it also appears to realize this is a moment to reset ties with the United States in its favor, analysts said. The incident has given space to right-wing, Islamist voices that have long called for the army and the government to sever ties with America and cut off the supply lines.
"The timing of this incident allows Pakistan to ratchet up pressure on the U.S., although it's not clear what the Pakistanis actually want," said Tim Hoyt, counterterrorism chair at the Naval War College in Newport, R.I.
Anthony Cordesman, an analyst for the Center for Strategic and International Studies in Washington, said this crisis likely "will get papered over" with some sort of U.S. or NATO apology and a "bribe in the form of better aid flows."
"In the process, however, the U.S. will face even less prospect that Pakistan will really crack down on insurgent groups in the border area, or stop seeing Afghanistan as an area where it competes with India and which is useful for strategic depth in some future war with India," Cordesman said.
Last year, Pakistan closed one of the border crossings for 10 days after a U.S. chopper killed two Pakistani soldiers on the border in a friendly fire incident. Militants then attacked dozens of the stranded supply trucks that were lined up by the side of the road. After 10 days, the U.S. apologized and Pakistan reopened the border.
Associated Press writers Zarar Khan and Asif Shahzad in Islamabad, Deb Riechmann in Kabul and Kimberly Dozier and Pauline Jelinek in Washington contributed to this report.