A US military refuelling aircraft crashed into a mountain in Pakistan while trying to land at a US base in Afghanistan, killing seven marines on board.
The KC-130 crashed while making a landing approach at Shamsi, Pakistan, about 20 to 30 miles northeast of Panjur, Pakistan, US Central Command said.
The flight came from Jacobabad, Pakistan, and was on a multi-stop supply run when it crashed into mountains at about 3,000 feet, making search-and-rescue efforts difficult, defence officials said.
"Our hearts and prayers go out to the families of the soldiers," President Bush said. "But I want to remind them that the cause that we are now engaged in is just and noble. The cause is freedom and this nation will not rest until we have achieved our objective".
The dead men were identified as Capt Matthew W Bancroft (29) of Shasta, California; Capt Daniel G McCollum (29) of Richland, South Carolina; Gunnery Sgt Stephen L Bryson (35) of Montgomery, Alabama; Staff Sgt Scott N Germosen (37) of Queens, New York; Sgt Nathan P Hays (21) of Lincoln, Washington; Lance Cpl Bryan P Bertrand (23) of Coos, Oregon; and Sgt Jeannette L Winters (25) of Du Page, Illinois.
In a separate incident, the Navy said one of its S-3B Viking refuelling aircraft made an emergency landing on the USS Theodore Rooseveltin the North Arabian Sea when its landing gear collapsed. No one was hurt.
US warplanes again attacked an area in eastern Afghanistan they claim to be a al-Qaeda huge complex as the US military prepared to fly prisoners to a US base in Cuba, officials said.
One of the officials said the first planeload of al-Qaeda and Taliban prisoners, among 368 under US military control, could leave in days for the isolated US Navy base at Guantanamo Bay.
Defence Secretary Mr Donald Rumsfeld said this week extreme care would be used in moving dangerous and potentially suicide-ready members of bin Laden's al-Qaeda network.