Pakistan's military denied reports that NATO forces in Afghanistan came under fire before launching a cross-border attack that killed 24 Pakistani soldiers over the weekend.
This is not true. They are making up excuses. What are their losses, casualties? army spokesman Major-General Athar Abbas said in a mobile phone text message on Monday.
Tensions are running high at a time when deep cooperation is needed between the NATO mission and Pakistan to stabilise Afghanistan as the United States tries to wind up the war there.
NATO described the killings as a tragic, unintended incident and said an investigation was underway. A Western official and an Afghan security official who requested anonymity said NATO troops were responding to fire from across the border.
Pakistan's military said the strike was unprovoked and has reserved the right to retaliate.
It's possible both explanations are correct: that a retaliatory attack by NATO troops took a tragic, mistaken turn in harsh terrain where differentiating friend from foe can be difficult.
After a string of deadly incidents in the lawless and confusing border region, NATO and Pakistan set up a hotline that should allow them to communicate in case of confusion over potential targets, or if they believe they are coming under fire from friendly forces.
It is not clear if the hotline was used, either before or after the strike that killed the Pakistani soldiers.
The attack was the latest perceived provocation by the United States, which infuriated Pakistan's powerful military in May with a unilateral special forces raid that killed al Qaeda leader Osama bin Laden.
Washington had been trying to repair ties badly damaged by the bin Laden affair and several other issues -- including accusations that Pakistan's military spy agency was backing militants who bomb American targets in Kabul.
Last month, U.S. Secretary of State Hillary Clinton visited Islamabad and held a town hall meeting to try and win over Pakistanis, held talks with her counterpart and called on all sides to work for peace in Afghanistan.
Any goodwill secured from the trip probably evaporated after the NATO strike, which fuelled a wave of anti-American sentiment in Pakistan.
Aside from growing anger on the street, newspaper editorials are filled with sharp criticism of the United States and NATO.
This is time for U.S./NATO/ISAF (International Security Assistance Force in Afghanistan) forces to understand the dark side of wanting to go it alone and think about accepting Pakistani offers for enhanced coordination, said The News.
The mass-circulation Urdu language press went further.
We have to send a clear and unequivocal message to NATO and America that our patience has run out. If even a single bullet of foreign forces crosses into our border, then two fires will be shot in retaliation, said Jang newspaper.
God forbid in future if something like this happened then our armed forces have to give a befitting response.
The NATO strike has shifted attention away from what critics say is Pakistan's failure to go after militants who cross the border to attack U.S.-led NATO and Afghan forces in Afghanistan.
Pakistan vowed to back the U.S. global war on militancy launched after al Qaeda's September 11, 2001 attacks on the United States, and won billions of dollars in aid in return.
But the unstable, nuclear-armed country has often been described as an unreliable ally, and the United States has had to resort to controversial drone aircraft strikes against militants on Pakistani territory to pursue its aims.
U.S. frustrations grew so much that President Barack Obama ordered that the raid that killed bin Laden deep inside Pakistan be kept secret, knowing it could make the United States even more unpopular in Pakistan.
Pakistan shut down NATO supply routes into Afghanistan in retaliation for the weekend shooting incident, the worst of its kind since Islamabad uneasily allied itself with Washington in 2001.
Pakistan is the route for nearly half of NATO supplies shipped overland to its troops in Afghanistan. Land shipments account for about two thirds of the alliance's cargo.
A similar incident on Sept 30, 2010, which killed two Pakistani service personnel, led to the closure of one of NATO's supply routes through Pakistan for 10 days.
Few believe the strategic alliance between Pakistan and the United States will break, even though the aggrieved military -- the South Asian nation's most powerful institution -- may now feel it needs to assert itself.
Both sides are likely to opt for damage control and then confidence-building measures -- the usual pattern in a frequently troubled relationship.
(Writing by Michael Georgy; Editing by Raju Gopalakrishnan)