The United States Air Force (USAF) says the beleaguered F-35A Lightning II has achieved combat readiness.

“I am proud to announce this powerful new weapons system has achieved initial combat capability,” said General Hawk Carlisle.

“The F-35A will be the most dominant aircraft in our inventory, because it can go where our legacy aircraft cannot and provide the capabilities our commanders need on the modern battlefield.”

The F-35A has been dogged by controversy for its entire development period, with cost overruns, flawed designs, failed tests, international espionage and missed deadlines getting in the way.

The authorities are celebrating the fighter’s first air-to-air kill after an F-35A launched an air-to-air missile to destroy a drone in a sortie over California.

“It's been said you don't really have a fighter until you can actually hit a target, and we crossed that threshold with the first air-to-air weapon delivery of an AIM-9X. This successful test demonstrates the combat capability the F-35 will bring to the U.S. military and our allies,” said F-35A pilot Major Raven LeClair.

Lockheed Martin is still developing the F-35B (vertical takeoff) and F-35C (catapult-assisted takeoff) variants of the F-35 platform, but neither has been certified combat ready.

Australia still plans to buy 72 F-35 Lightning Joint Strike Fighters at a cost of around $17 billion, despite the scheme being described as having “all the hallmarks of a Ponzi scheme” at a recent Senate inquiry investigating the acquisition.