What Is the F-35? The Stealth Fighter Explained

The F-35 Lightning II is a single-seat, single-engine stealth fighter built by Lockheed Martin to do three jobs in one airframe: fight other aircraft, strike targets on the ground and gather intelligence. It comes in three versions and is flown by the United States and a growing group of allies.

More than 1,375 jets had been delivered by early October 2026, according to Lockheed Martin, and the fleet has passed one million flight hours. This guide answers the basic question, what is the F-35, and sets out what makes it different from older fighters, who flies it and where the programme stands.

What is the F-35?

The F-35 is a fifth-generation fighter, the label used for aircraft that combine low radar visibility with networked sensors and heavy onboard computing. It grew out of the Joint Strike Fighter programme of the 1990s, which set out to replace several older types, among them the F-16, the A-10, the AV-8B Harrier and early F/A-18 Hornets, with one family of jets. Lockheed Martin’s X-35 beat Boeing’s X-32 in October 2001, and the first F-35A flew on 15 December 2006.

Lockheed Martin is the prime contractor. Northrop Grumman builds the centre fuselage and the radar, BAE Systems supplies the aft fuselage and the electronic warfare suite, and Pratt & Whitney makes the F135 engine. The name Lightning II honours the Lockheed P-38 Lightning of the Second World War and Britain’s English Electric Lightning. The full numbers are in our F-35 specifications and cost guide.

What makes the F-35 different from older fighters?

Three things set it apart. The first is stealth. The shape of the airframe, radar-absorbing materials and weapons carried inside the fuselage all cut the distance at which enemy radars can detect and track the jet.

The second is its sensors. An active electronically scanned array radar (see how AESA radar works), six infrared cameras spread around the airframe and an electro-optical targeting system all feed one computer. It merges what they see into a single picture, shown on a large touchscreen and in the pilot’s helmet. That sensor fusion is the aircraft’s main selling point: the pilot manages the fight instead of working each sensor in turn.

The third is networking. An F-35 shares what it sees with other F-35s over a hard-to-detect data link and with other forces over Link 16. In practice it often acts as a scout and coordinator for older fighters, ships and ground-based air defences.

What are the three F-35 variants?

All three versions share the same engine core, sensors and software. They differ in how they take off and land, and that drives differences in fuel load, range and weight.

What is the F-35 used for?

Air forces use the F-35 for air-to-air combat, precision strike, hunting air defence radars and missile sites, close air support, reconnaissance and electronic attack. The F-35A has also been certified to carry the B61-12 nuclear bomb, a clearance completed in October 2023.

Israel was the first to use the jet in combat, in 2018, and US Marine Corps F-35Bs struck targets in Afghanistan the same year. It has since flown combat missions over Iraq, Syria, Yemen and Iran. On 4 March 2026 an Israeli F-35I shot down an Iranian Yak-130 over Tehran, the type’s first kill of a crewed aircraft. On 19 March a US F-35 made an emergency landing after it was reportedly hit by Iranian fire; US Central Command said the jet landed safely and the pilot was in stable condition.

How many F-35s are there, and who flies them?

Lockheed Martin lists more than 1,375 aircraft delivered, operating from 55 bases, with over 3,610 pilots and 21,980 maintainers trained. The company delivered a record 191 jets in 2025. The United States is by far the largest customer, with a programme of record of 2,456 aircraft across the Air Force, Navy and Marine Corps.

Twenty countries are in the programme: the United States, Australia, Belgium, Canada, the Czech Republic, Denmark, Finland, Germany, Greece, Israel, Italy, Japan, the Netherlands, Norway, Poland, South Korea, Romania, Singapore, Switzerland and the United Kingdom. Several of them are still waiting for their first jets.

Not every interested country got in. Turkey, an original partner, was removed in July 2019 after it bought the Russian S-400 air defence system. In September 2026 the US State Department approved a possible $24.3 billion sale of 48 jets to Saudi Arabia, which still has to pass congressional review.

What does it cost, and what are the problems?

The latest production contracts, Lots 18 and 19, put the average flyaway cost at $92.0 million for an F-35A, $121.4 million for an F-35B and $110.8 million for an F-35C, engine included, according to Air & Space Forces Magazine. Buying the jet is the smaller part of the bill. The Pentagon estimates the programme will cost more than $2 trillion through 2088, most of it for operating and sustaining the fleet.

The main complaints are readiness and software. A Government Accountability Office report in June 2026 found the share of jets able to fly at least one mission fell from 67% in 2021 to 44% in 2025. The TR-3 hardware and software upgrade, the base for the Block 4 improvements, is years late: the Pentagon’s test office reported that no combat-capable TR-3 jets had been delivered by September 2025, and the first Block 4 capabilities are now expected around 2031.

Frequently asked questions

What does F-35 stand for?

F is the US military designation for a fighter and 35 is the design number, carried over from the X-35 demonstrator. The official name is Lightning II.

Who makes the F-35?

Lockheed Martin, with Northrop Grumman, BAE Systems and Pratt & Whitney as its main partners. Final assembly takes place in Fort Worth, Texas, in Cameri, Italy, and in Nagoya, Japan.

Is the F-35 a fifth-generation fighter?

Yes. It combines stealth, sensor fusion and networking, the features usually used to define the fifth generation.

How fast is the F-35?

Mach 1.6, or about 1,200 mph, for all three variants.

How many countries fly the F-35?

Lockheed Martin counts the United States and 19 allied nations. Some of them have ordered the jet but have not yet received it.

Is the F-35 better than the F-22?

They do different jobs. The F-22 is faster and more agile and is built for air-to-air combat. The F-35 has newer sensors, carries a wider range of weapons and, unlike the F-22, is exported.

How much does one F-35 cost?

About $92 million for an F-35A in Lots 18 and 19, engine included. The F-35B and F-35C cost more.