Updated

An approaching storm prompted the U.S. military to place its base in Guantanamo Bay, Cuba, under an alert Wednesday and cancel several days of pretrial hearings in the case of five prisoners charged in the Sept. 11 attacks.

The military planned to evacuate about 200 people, including legal teams and relatives of Sept. 11 victims, who traveled to the remote base in southeast Cuba to attend hearings that had been scheduled to start Thursday, said Army Lt. Col. Joseph Todd Breasseale, a Pentagon spokesman.

The judge in the case, Army Col. James Pohl, issued an order postponing the hearings until further notice due to a "concern for the safety and welfare of all personnel."

The Navy placed the base, which has about 6,000 personnel in all, on an alert Wednesday due to the approach of Tropical Storm Isaac, which was expected to bring winds of nearly 60 mph (100 kph) within 72 hours. Officials warned military and civilian personnel to prepare emergency shelters and secure loose objects that could become projectiles in heavy wind.

A prison spokesman, Navy Capt. Robert Durand, says all 168 prisoners will be in buildings that can sustain hurricane-force winds and that the military has plans in place to provide shelter for all troops and civilians.