"We’re all seized with the problem,” Dempsey was quoted as saying by the American Forces Press Service. “You can’t whitewash it. We can’t convince ourselves that we just have to work harder to get through it. Something has to change."
Dempsey made the comments on Sunday, on a flight from Romania to Turkey.
He said America's Afghan allies need to be as concerned about the insider attacks as the U.S. is: "We have to get on top of this. It is a very serious threat to the (Afghanistan) campaign.”
The attacks on U.S. troops by Afghan soldiers and police show no sign of abating.
On Sunday, an Afghan soldier fired on a vehicle he apparently believed was carrying NATO troops. An international civilian worker was wounded in the attack..
On the same day, an Afghan police officer shot and killed four American troops in the southern city of Zabul.
The weekend of deadly attacks began Friday night, when 15 insurgents disguised in U.S. army uniforms killed two Marines, wounded nine other people and destroyed six Harrier fighter jets at a major U.S. base in the south, military officials said.
On Saturday, a gunman in the uniform of a government-backed militia force shot dead two British soldiers in Helmand province in the southwest.
The Associated Press reports that more than 50 international service members have died at the hands of their Afghan allies or those who have infiltrated their ranks so far this year. At least 12 such attacks came in August alone, leaving 15 dead.