KABUL, Afghanistan (AP) -- The third apparent insider attack in as many days has killed four U.S. service members in southern Afghanistan.
NATO says at least one Afghan police officer turned his gun on coalition troops at a remote checkpoint, before escaping.
In all, eight troops have died in such attacks the past three days.
Recent months have seen a string of such insider attacks by Afghan forces against their international counterparts. The killings have imperiled the military partnership between Kabul and NATO, a working relationship that is key to the handover of security responsibilities to Afghan forces as international troops draw down.
The most recent attacks also come amid an international uproar about an Internet video that mocks Islam.
There were two protests against the film in Afghanistan today, one in the capital, Kabul, and one in the western city of Herat. Both appeared to be going forward peacefully.