ISLAMABAD -- Confusion and a communication breakdown prevented Pakistan's airforce from scrambling to defend troops on the ground during the deadly NATO bombing last weekend of two border outposts, the military said Friday, responding to rare domestic criticism of the powerful institution.
The attack killed 24 Pakistani troops and pushed already strained ties between Washington and Islamabad over the future of Afghanistan close to rupture. Islamabad has closed its eastern border to NATO supplies traveling into landlocked Afghanistan and said it is reviewing its cooperation with Washington.
Thousands of Islamist extremists took to the streets across the country after Friday prayers, some shouting they would join the army in a battle with the U.S.-led coalition in Afghanistan. The chants were a worrying sign for the West, reflecting how the anger over the incident is uniting hard-liners and the military.
Others rallied against the country's already weak government for its alliance with Washington.
The Pakistani military, which eats up most of the country's budget and is accountable to no one, has said Saturday's border attack was an "act of deliberate aggression" that went on for close two hours. It has also said that Pakistani commanders contacted and pleaded with coalition commanders to stop firing.
NATO and U.S. officials have disputed that account, which has triggered uncomfortable questions in this South Asian country over why Pakistan's own fighter jets and helicopters stationed close to the border did not take off to defend the ground troops during the attack.
The military has said troops did fire back at the NATO choppers when they attacked.
A Pakistani military statement on Friday said the response could have been more "effective" if the airforce had been called in, but this was not possible because of a "breakdown of communication" and confusion at "various levels" within the organization.
U.S. officials expressed their condolences over the loss of life and denied the Pakistan army was deliberately targeted.
But they have not apologized, saying it would not be appropriate before an investigation into the incident has been completed. In the past, NATO and the US has complained that militants along the border are helped or tolerated by Pakistani soldiers.
Demonstrations Friday took place around Pakistan, with one of the largest in Karachi, the country's commercial hub.
Sunni extremist group Sipah-e-Sahaba, subject to a government ban, largely ignored, because of its links to al-Qaida, rallied in the Karachi downtown area.
Aurangezeb Farooqi, a leader of the group, asked the 2,000 protesters whether they were ready to join the army in fighting Americans. Many raised their fists in response and shouted "God is great!". Some held up placards saying: "There is only one treatment for America: jihad, jihad," or holy war.
U.S. officials have told The Associated Press that Saturday's incident occurred when a joint U.S. and Afghan patrol requested backup after being hit by mortar and small arms fire by Taliban militants. Before responding, the patrol first checked with the Pakistani army, which reported it had no troops in the area, they said.
Pakistani officials have refuted this claim and said U.S. forces must have known they were attacking Pakistani soldiers because the posts were clearly marked on maps given to NATO and the two sides were in contact immediately before and during the airstrikes.
Pakistan's military also faced criticism after the May 2 unilateral American helicopter-borne raid that killed Osama bin Laden, with questions -- yet unanswered -- over how the aircraft were able to fly deep into Pakistani territory without the knowledge of the airforce.
Associated Press writer Ashraf Khan in Karachi contributed to this report.