Afghan insider attack kills 4 US troops Sunday

KABUL, Afghanistan (AP) --The escalating violence in Afghanistan -- including a NATO airstrike that killed eight Afghan women and girls gathering firewood -- is straining the military partnership between Kabul and NATO. And it comes as the U.S. begins to withdraw thousands of troops sent three years ago to route the Taliban from southern strongholds.

Officials say Afghan police killed four American soldiers coming to their aid after a checkpoint attack Sunday, the third assault by government forces or insurgents disguised in military uniforms in as many days.

The U.S. military's top general says the problem of rogue Afghan soldiers and police turning their guns on American and allied troops is a "very serious threat" to the war effort.

Gen. Martin Dempsey says the Afghan government needs to take the problem as seriously as do U.S. and NATO commanders and officials.

The Joint Chiefs of Staff chairman says "you can't whitewash" the problem, and that it can't be fixed by just working harder.

Dempsey, who's traveling in Europe, tells American Forces Press Service that "something has to change."

This year, 51 international service members have died at the hands of their Afghan allies or those who have infiltrated their ranks. At least 12 such attacks came in August alone, leaving 15 dead.