The U.S. military said it had grounded the entire fleet of 97 Lockheed Martin Corp F-35 fighter jets until completion of additional inspections of the warplane’s single engine built by Pratt & Whitney, a unit of United Technologies Corp.

The Pentagon’s F-35 program office, Air Force and Navy issued directives on Thursday ordering the suspension of all F-35 flights after a June 23 fire on an Air Force F-35A jet at Eglin Air Force Base in Florida.

The Pentagon said U.S. and industry officials had not pinpointed the cause of the fire, which occurred as a pilot was preparing for takeoff. The pilot was not injured. […]