President Barack Obama saw first hand the human cost of the Afghanistan war as he welcomed home on Thursday 18 soldiers and Drug Enforcement Administration agents killed in Afghanistan this week.

Obama, flying in his Marine One presidential helicopter, landed shortly after midnight in Dover Air Force Base in Delaware, home of the United States'' largest military mortuary and main point of entry for U.S. service members killed abroad.

Minutes earlier, an Air Force C-17 transport aircraft landed in the base, carrying the bodies of eight Army soldiers killed by a roadside bomb and seven soldiers and three DEA agents killed in a helicopter crash, according to the military.

Obama went into a meeting with families of the killed soldiers and agents in a chapel on the base, military officials said.

Later, a military chaplain will accompany Obama and other officials onboard and say a prayer over each flag-draped casket before it is transferred out of the aircraft, the officials said.