The Joint Strike fighter (JSF) is a program designed to develop a family of stealthy, next- generation replacement strike fighter aircraft for the USAF, USN, USMC and the UK Royal navy and Royal Air Force.

The Joint Advanced Strike Technology program ended its research phase in December 1994.

The JSF program entered its current phase, the Concept Demonstration Phase in November 1996, when two contractors, Boeing (X-32) and Lockheed Martin (X-35), were selected to build and fly Concept- Demonstration aircraft.

There were two aircraft, the X-32A CTOL concept demonstrator for the USAF and US Navy, and the X-32B STOVL concept demonstrator for the USMC and Royal Navy. Unlike the Lockheed Martin X-35, there were no airframe changes required to demonstrate US Navy aircraft carrier (CV/CTOL) approach capabilities - the X-32A performed both roles.

First flight of the Boeing X-32A was on September 18, 2000 a flight from Palmdale, CA to Edwards Air Force Base, CA.

The first air-air refueling with a McDonnell Douglas KC-10A Extender was on December 19, 2000.

With the X-32A were planned for the test program, 30 flights conventional take-off and landing and 30 flights of carrier capable take-off and landings.

The X-32B first flight March 29,2001, completed the first vertical landings following transition from conventional to vertical flight at the US Navy's Patuxent River, MD, test facility at June 27, 2001. Since March 2001 it has flown 78 flights, 43,2 hours in the test program, that ended on July 8,2001.  

The Governments Joint Strike Fighter decision on October 26, 2001, was a disappointment for Boeing, the winner of the competition is the Lockheed Martin X-35.