The U.S. Air Force says an investigation into engine trouble during a recent Delta rocket launch will delay the launch of its X-37B mini-shuttle.

The launch, originally set for next Tuesday, is now scheduled for Dec. 11, Florida Today reported.

Engine trouble was encountered during the Oct. 4 launch of a ULA Delta IV rocket and an Air Force Global Positioning System satellite when reduced thrust levels were detected.

The Atlas V rocket set for the mini-shuttle launch utilizes a second-stage engine similar to the one on the Delta IV rocket.

Although the GPS satellite successfully reached orbit, mission managers said they want to be sure a similar problems doesn't threaten the success of the X-37B Orbital Test Vehicle launch.

The latest delay is the third for the mini-shuttle launch, which was originally scheduled for Oct. 25.