It is the leading cause of fatalities . More than 6,700 U.S. troops have died in the wars in Iraq and Afghanistan . At least 20 other countries have lost troops in the war . Six wreaths are engraved on the Tomb of the Unknowns , in Arlington National Cemetery .
More than 6,700 U.S. troops have died in the wars in Iraq and Afghanistan . At least 20 other countries have lost troops in the war . Six wreaths are engraved on the Tomb of the Unknowns , in Arlington National Cemetery .