The U.S. military says it has grounded its entire fleet of F-35 fighter jets until it completes an investigation into a runway fire involving one of the jets last week.
The Defense Department said additional inspections of the F-35 engines have been ordered.
Last week's fire at Elgin Air Force Base in Florida was only the latest in a series of technical problems and delays that have plagued the Pentagon's $396 billion fighter jet program. It is the costliest weapons program in U.S. military history. Additional delays could raise costs even further.
An in-flight oil leak prompted an inspection of the entire fleet last month.
The Defense Department said the return to flight of the jet will be determined based on inspection results and analysis of engineering data.
A statement on the F-35.com website says the fighter jet "can operate in virtually any battle situations, from paved runways to aircraft carriers to roads and austere bases." The website says no other fighter has "the versatility and combined capabilities of the multi-role F-35."