The Harrier II Plus was developed through a three-nation agreement among the United States,Spain and Italy. McDonnell Douglas, British Aerospace and Rolls-Royce proposed the AV-8B as a successor to the AV-8A. It is equipped with an increased-thrust version of the Rolls-Royce Pegasus F402-RR-408 engine, which is found in night-attack Harrier IIs.