US President Barack Obama says he's confident there will be a detailed and thorough investigation into an army helicopter crash off the coast of Florida.
Mr Obama spoke with Major General Joseph Osterman, who heads the Marine Corps special forces, and Major General Glenn Curtis of the Louisiana National Guard.
Seven Marines and four soldiers are believed to have been killed in the Black Hawk crash during a night-time training mission.
The White House says Mr Obama expressed his condolences to the families and fellow service members of those killed. White House spokesman Josh Earnest says the president also conveyed his deep appreciation for the sacrifices made by US troops.
Fog in the area reduced visibility to two miles or less when the helicopter went missing on Tuesday night.