In this photograph taken on July 29, 2011 a US military Chinook helicopter lands at Forward Operating Base in Arghandab district southern Afghanistan. Thirty-one US special forces and seven Afghans died when the Taliban shot down their helicopter, officials said on August 6, 2011, the deadliest incident yet for foreign troops in a decade-long war. All were killed during an anti-Taliban operation late Friday when a rocket fired by the insurgents struck their Chinook helicopter in Wardak province, southwest of the capital Kabul, as they prepared to leave after a firefight. AFP PHOTO / ROMEO GACAD *** Local Caption *** 563901-01-08.jpg
In this file photograph taken on July 29, 2011, a US soldier mans a machine gun on a US military Chinook helicopter as it heads to Kandahar military base while transporting troops around southern Afghanistan.
In this photograph taken on July 29, 2011, a US military Chinook helicopter transport cargo over Arghandab district. Thirty-one US special forces and seven Afghans died when the Taliban shot down their helicopter, officials said on August 6, 2011/
Virginia Beach residents Tom Hall, left, and Mark Janik, centre, watch as news about the Navy Seal Team Six helicopter accident is displayed on a television at a bar in Virginia Beach , Va., Saturday, Aug. 6, 2011.
U.S. President Barack Obama holds a conference call from Camp David, Maryland, in this August 6, 2011 photo release. A NATO helicopter crashed during a battle with the Taliban in Afghanistan, killing 31 U.S. soldiers and seven Afghans.