The Joint Strike Fighter (JSF) is a joint, multinational acquisition program for the United States Air Force (USAF), Navy, Marine Corps and eight cooperative international partners. It was created to replace various aircraft while keeping development, production and operating costs down. The objective is to develop a technically superior and affordable fleet of aircraft that would be capable of a wide range of missions in a variety of theaters. The program began in November 1996 with a 5-year competition between Lockheed Martin and Boeing to determine the most capable and affordable preliminary aircraft design. On October 26, 2001, the contract was awarded to Lockheed Martin, whose X-35 experimental aircraft outperformed Boeing's X-32.

The F-35 Lightning II, which descended from the X-35, has become synonymous with the JSF program. It is a single-seat, single-engine, stealth-capable military strike fighter that can perform multiple roles such as close air support, tactical bombing and air-to-air combat. The name Lightning II was officially announced by the USAF on July 7, 2006, in honor of Lockheed's P-38 Lightning and the English Electric Lightning. Expected to be the largest military aircraft procurement ever, the F-35 will replace a wide range of aging fighter and strike aircraft. It is being designed and built by an aerospace industry team led by Lockheed Martin, with Northrop Grumman and BAE Systems as major partners. While the United States is the primary customer and financial backer of the F-35, the United Kingdom, the Netherlands, Italy, Canada, Denmark, Norway, Australia and Turkey have contributed toward the development costs of the program.