An Afghan soldier shot dead two US soldiers and one US civilian on Saturday, the latest "insider attack" to shake efforts by the two armies to work together to defeat the Taliban insurgency, Agence France Presse reports.
The killings in the eastern province of Paktika came on the same day that one Italian soldier died when a grenade was thrown into an armoured vehicle in Farah province, in the far west of the country.
Scores of foreign soldiers have been killed in insider attacks in Afghanistan, breeding fierce mistrust and threatening to derail the training of local forces to take over security duties ahead of NATO's withdrawal next year.
The threat has become so serious that foreign soldiers working with Afghan forces are regularly watched over by so-called 'guardian angel' troops to provide protection from their supposed allies.
The Paktika provincial government issued a statement saying "a verbal dispute erupted" between the Afghan soldier and a US soldier in the district of Khair Kot.
It said the Afghan man killed three US service members from the NATO-led International Security Assistance Force and wounded three others before being shot dead himself.
"Initial information indicates that the incident followed an argument, and the soldier was not connected with the armed opposition," the statement added.
ISAF officials say that most insider attacks stem from personal grudges and cultural misunderstandings rather than Taliban insurgent plots.
An ISAF statement confirmed the incident, saying that two US soldiers and one US civilian had died. It gave no further details on the role of the civilian.
The Punch