In the second green-on-blue attack of the weekend, four NATO troops were killed on Sunday by members of the Afghan security forces, The New York Times reports.
This latest attack took place in Afghanistan's Zabul province. Although most of the NATO troops stationed in that province are Americans, the coalition has not announced the nationalities of the latest victims.
On Friday, two British soldiers were killed in Helmand Province by a member of the Afghan Local Police. The attacker was killed by returning fire.
Insider attacks have been on the rise this year in Afghanistan, claiming the lives of dozens of Americans. The Pentagon is investigating the root of these attacks and boosting security to prevent further shootings. With this weekend's deaths, the number of coalition forces killed by green-on-blue attacks rose to 51 this year. Last year, 35 were killed by similar attacks.
Two U.S. Marines were also killed on Friday from an assault by the Taliban on a fortified NATO base in the Helmand province.
Coalition authorities say the 15 insurgents who attacked the airfield wore U.S. Army uniforms and destroyed six Harrier fighter jets, the Associated Press reports. Fourteen of the 15 were killed, while one was captured. Authorities called the attackers "well equipped, trained and rehearsed," according to AP.
After the attack, a Taliban spokesman said insurgents were targeting British Prince Harry, who was deployed back to Afghanistan just a week ago, the Los Angeles Times reports. The prince, known as "Capt. Wales" in the military, was in a "secure location" miles away, officials said.
The Taliban also claimed the attack was in response to an anti-Islamic film produced in the U.S., which has inspired violent protests in Egypt, Libya and elsewhere.