The strike came on the same day that one Italian soldier was killed and three others were wounded when a grenade was thrown into their armoured vehicle in the western province of Farah.
Scores of foreign soldiers have been killed in insider attacks, breeding fierce mistrust and threatening to derail the process of training Afghan 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.
"Three ISAF (International Security Assistance Force) members were killed when an individual wearing ANSF (Afghan National Security Force) uniform turned his weapon on them and opened fire," a spokesman told AFP.
ISAF said on its Twitter feed that it was "investigating a possible insider attack in eastern Afghanistan".
Military officials in Kabul confirmed that the three dead soldiers were from the United States.
Local officials in the province of Paktika said that the incident had taken place in the district of Khair Kot.
The Taliban launched their annual spring offensive at the end of April, marking a crucial period for Afghanistan as local security forces take the lead in offensives against the insurgents.
The Islamist militants said multiple suicide bombings and insider attacks by Afghan soldiers on NATO-led troops would be used to inflict maximum casualties.
Afghan soldiers and police are taking on responsibility for battling the militants from 100,000 NATO combat troops who will leave by the end of next year -- 13 years after a US-led invasion brought down the Taliban regime.
"Today at around 10:30 am (local time), an enemy on a motorcycle threw a grenade on a convoy of Italian forces who were driving on a patrol in Farah city," Abdul Rahman Zhowandi, Farah provincial spokesman, told AFP.
The Italian defence ministry and military said the attack happened as the convoy was returning to base.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
