U.S. troops in Afghanistan are being guarded more closely and are taking other steps to protect themselves from attacks by Afghan troops.
A senior military official said Wednesday that the top commander in Afghanistan, Gen. John Allen, ordered the measures in recent weeks after a series of cases in which U.S. and other coalition forces were killed by Afghan soldiers. Some of the killings were believed to be triggered by the accidental burning of Qurans and other religious materials.
The new measures include the use of so-called "guardian angels" -- troops who guard others as they sleep. Americans can now carry weapons in some ministries and have moved their desks so they can keep an eye on the door. Two officers were killed at their desks in the Interior Ministry in Kabul.