(CBS News) It has happened again.
Two American military men were killed in Afghanistan today, by an Afghan policeman.
It happened in a village in Afghanistan's far west, where U.S. troops were teaching the Afghans to take over their own security.
This is just the latest of these attacks by troops who were supposed to be our allies. They took the lives of 12 Americans in 2010, last year that number doubled and already this year there have been 25 who have been killed.
This time, a brand new policeman stepped forward to receive his weapon and immediately turned it on his trainers, killing two members of U.S. special forces.
It's a kick in the gut of the U.S. strategy of training afghans to take over the fighting so Americans can come home. For families back home, it produces an almost unwatchable outburst of rage and grief.
"I don't understand what happened," said the mother of Marine Lance Cpl. Gregory Buckley, who was gunned down by an Afghan policeman last week. "I don't know why he's not here. I don't know why. I want to know answers. I want to know why he's not here."
The rest of us can only imagine her grief but everyone can agree with what she is saying.
"I'm so proud of my son, but this shouldn't have happened to my son and I want answers," she said.
A spontaneous wake occurred on the front lawn of their home on Long Island. The local baseball team walked over from the field across the street and stood in stunned silence as Buckley's father, gasping for breath, tried to comprehend what had happened.
"He was gunned down," he said. "He was gunned down with a weapon that we supplied."
Statistically, insider attacks are rare when compared to the tens of thousands of interactions which take place each day between the 84,000 American troops and 332,000 Afghan security forces. But statistics mean nothing to the Buckleys.
Faced with a continuing threat of insider attacks, the commanding general in Afghanistan has ordered his troops to carry loaded weapons at all times, even on base.