US Air Force F-35 cannon has been successfully tested. The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth-generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability.[7][8] The F-35 has three main models; the F-35A is a conventional takeoff and landing variant, the F-35B is a short take-off and vertical-landing variant, and the F-35C is a carrier-based variant. The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. It is being designed and built by an aerospace industry team led by Lockheed Martin. The F-35 took its first flight on 15 December 2006. The United States plans to buy 2,443 aircraft. The F-35 variants are intended to provide the bulk of its tactical airpower for the U.S. Air Force, Marine Corps and Navy over the coming decades. JSF development is being principally funded by the United States with additional funding from partners. The partner nations are either NATO members or close U.S. allies. The United Kingdom, Israel, Italy, The Netherlands, Australia, Canada, Norway, Denmark, and Turkey are part of the active development program; Japan has ordered the F-35, while Singapore may also equip their air force with the F-35.[9][10][11][12][13][14][15] The United States Air Force (USAF) is the aerial warfare service branch of the United States Armed Forces and one of the seven American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on 18 September 1947 under the National Security Act of 1947.[5] It is the most recent branch of the U.S. military to be formed, and is the largest and one of the world's most technologically advanced air forces. The USAF articulates its core functions as Nuclear Deterrence Operations, Special Operations, Air Superiority, Global Integrated ISR, Space Superiority, Command and Control, Cyberspace Superiority, Personnel Recovery, Global Precision Attack, Building Partnerships, Rapid Global Mobility and Agile Combat Support.[6] The U.S. Air Force is a military service within the Department of the Air Force, one of the three military departments of the Department of Defense. The USAF is headed by the civilian Secretary of the Air Force, who is appointed by the President with the advice and consent of the Senate. The highest-ranking military officer in the Department of the Air Force is the Chief of Staff of the Air Force who exercises supervision over Air Force units, and serves as a member of the Joint Chiefs of Staff. Air Force combat forces are assigned, as directed by the Secretary of Defense, to the Combatant Commanders, and neither the Secretary of the Air Force nor the Chief of Staff have operational command authority over them. A fighter aircraft is a military aircraft designed primarily for air-to-air combat against other aircraft,[1] as opposed to bombers and attack aircraft, whose main mission is to attack ground targets. The hallmarks of a fighter are its speed, maneuverability, and small size relative to other combat aircraft. Many fighters have secondary ground-attack capabilities, and some are designed as dual-purpose fighter-bombers; often aircraft that do not fulfill the standard definition are called fighters. This may be for political or national security reasons, for advertising purposes, or other reasons.[2] A fighter's main purpose is to establish air superiority over a battlefield. Since World War I, achieving and maintaining air superiority has been considered essential for victory in conventional warfare.[3] The success or failure of a belligerent's efforts to gain air supremacy hinges on several factors including the skill of its pilots, the tactical soundness of its doctrine for deploying its fighters, and the numbers and performance of those fighters. Because of the importance of air superiority, since the dawn of aerial combat armed forces have constantly competed to develop technologically superior fighters and to deploy these fighters in greater numbers, and fielding a viable fighter fleet consumes a substantial proportion of the defense budgets of modern armed forces.[4] The United States of America (USA or U.S.A.), commonly referred to as the United States (US or U.S.), America, or simply the States, is a federal republic[10][11] consisting of 50 states, 16 territories, a federal district, 310 Indian reservations and various overseas extraterritorial jurisdictions. The 48 contiguous states and the federal district of Washington, D.C. are in central North America between Canada and Mexico. The state of Alaska is the northwestern part of North America, west of Canada and east of Russia, which is across the Bering Strait in Asia, and the state of Hawaii is an archipelago in the mid-North Pacific. The country also has five populated and nine unpopulated territories in the Pacific and the Caribbean.