The Pentagon plans to have the F-35 fighter jet replace most of the combat aircraft fleet of the US Air Force, Navy and Marine Corps by the end of the decade.

The single-engine fighter is considered a fifth-generation aircraft because of its advanced software and stealthy attributes aimed at evading radar in hostile territory.

US strategists often mention China's growing military power when justifying the need for such a high tech plane, while Beijing is also pursuing its own stealthy fifth-generation warplane.

The US program calls for producing 2,443 aircraft for the American military and several hundred others for eight international partners who have invested in the project, as well as at least two customers, Japan and Israel.

The eight countries helping to fund the aircraft are Australia, Britain, Canada, Denmark, Italy, the Netherlands, Norway and Turkey.

One version of the plane is designed for the Air Force, the F-35A, which will replace F-16 and F-18 fighter-bombers and the A-10 Thunderbolt ground-attack aircraft.

A second variant, the F-35C, is meant for aircraft carriers and will take the place of the US Navy's F/A-18s. A third version, the F-35B, is a jump jet that is due to succeed the military's aging Harriers.

With 80 percent of the parts common to all three variants, the production costs of the F-35 Joint Strike Fighter were expected to be reduced compared to previous weapons programs.

But since the contract was awarded to aerospace giant Lockheed Martin in 2001, the cost of the program has doubled and the aircraft -- which was originally supposed to join the fleet this year -- will not be operational before the end of the decade.

Capable of reaching a speed of Mach 1.6 (about 1,900 kilometers or 1,180 miles per hour), the aircraft has a range of 1,100 kilometers (594 nautical miles) -- about 800 kilometers (432 nautical miles) for the F-35B -- but can be refueled in the air.

The plane can carry two air-to-air missiles and two precision-guided bombs in its bomb bay, and four other bombs or missiles under its wings.

Most of the countries that have declared an interest in the F-35 program are part of an international consortium in which participants share part of the development costs and are granted a role in production.

While US aerospace giant Lockheed Martin is the lead contractor for the project, Britain's BAE Systems will produce the rear section of the fuselage at its factory in Samlesbury.