The US Air Force (USAF) has accepted the first production-model Lockheed Martin F-35 Lightning II stealth fighter, known as the AF-7, into its fleet.

The jet will undergo a flight testing programme at US Edwards Air Force Base, California, US.

The F-35 Lightning II advanced multirole fighter integrates very low observable stealth with fighter speed and agility, fully fused sensor information, network-enabled operations and reduced sustainment costs.

The F-35 features supersonic launch of internal air-to-air missiles at a speed of Mach 1.6 and unique situational awareness with exceptional networking capability.

The USAF A-10 and F-16 fighter jets will be replaced by three distinct F-35 variants and a variety of fighters for at least nine other countries.

Eight additional F-35 production-models are being prepared for delivery.

The aircraft is being developed by Lockheed along with industrial partners, Northrop Grumman and BAE Systems.