A U.S. Army commander says recovering four soldiers from their submerged vehicle in swampland in Lithuania "will be a long and difficult" operation.

The troops, assigned to the 1st Brigade, 3rd Infantry Division, out of Fort Stewart, Georgia, were last seen aboard an M88 recovery vehicle before it was found submerged in deep mud and water.

General Mark Rutte made when he suggested that four U.S. soldiers who went missing while training in Lithuania had died.