Ironically, there has been NO apology from the U.S.-trained-and-funded Afghan military for the murders.
In 2009 Military personnel threw away, and ultimately burned, confiscated Bibles that were printed in the two most common Afghan languages amid concern they would be used to try to convert Afghans, a Defense Department spokesman said Tuesday.
Military Burns Holy Bible
So to sum it up:
Burn Korans on accident at U.S. base in Afghanistan –> U.S. troops killed by riots
Burn Bibles on purpose at U.S. base in Afghanistan –> Protects U.S. troops from being killed by riots