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 F-35 Lightning II, which is descended from the X-35, has become synonymous with the JSF program.