Pakistan is said to be pulling out of an international conference on the future of Afghanistan, after 24 of its soldiers were killed in a cross-border attack by NATO forces.
The incident, which happened on Saturday, has fuelled a wave of anti-American sentiment, with protests taking place throughout Pakistan.
The conference boycott comes after NATO supply routes were shut down.
The move has left hundreds of trucks stranded in Pakistan.
Convoys carry almost half of the alliance’s supplies overland to troops in Afghanistan.
Some drivers say they would now be happy to see the supply lines closed down for good.
NATO has described the deaths of the 24 Pakistani soldiers as a “tragic, unintended incident.”
Investigations are looking into what happened.
Losing Pakistan from next week’s conference in Germany is a diplomatic blow to Afghanistan and the nations fighting there.
It could mean Pakistan will not use its influence with Taliban militants to bring them to the peace table.
Saturday’s attack is the worst incident of its kind since Islamabad allied itself with Washington in 2001.