Published: Aug 09, 2011 6:53 PM EDT

DOVER AIR FORCE BASE, Del. (AP) - President Barack Obama is privately honoring the U.S. forces killed in the costliest attack of the Afghanistan war.
    
The president is at Dover Air Force Base in Delaware, where fallen troops come home. His trip was unannounced in a measure of security.
    
A total of 30 Americans and eight Afghans were killed Saturday when their helicopter was shot down by a Taliban insurgent using a rocket-propelled grenade.
    
No media coverage of the proceedings was to be permitted, on order of the military.

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