Lockheed Martin’s F-35 Fighter Jet has become the most expensive military project in the US history to date, but still can’t meet the Pentagon’s initial requirements and loses in capabilities to Russian Sukhoi Su-35 aircraft.

The Russian Sukhoi Su-35, acknowledged to be one of the best contemporary fighter jets, beats the American F-35 in “tactical” capabilities, a former US Department of Defense’s senior expert Michael Maloof revealed in an interview with the Iranian news outlet Press TV.

“They’ve discovered the stealth capability of the F-35 is not foolproof, that there are radar systems being incorporated in other aircraft… that can actually pick up the stealth-like aircraft,” Maloof said of some of the flaws in the American jets.

Except issues with a stealth mode in the jet, the F-35 Joint Strike Fighter program has a bunch of major additional flaws, according to the report conducted by Michael Gilmore, the Pentagon’s director of operational test and evaluation.

The issues include the warplanes’ shifted production schedule, the ability to synthesize information on the battlefield while keeping the jet flying.

In the report, Gilmore has put in question the practicability of the US’ “block buy” strategy that suggests purchasing of up to 450 F-35s before the jets are proven fully capable and ready for battle.

The first block will last for three years and will start in 2018. Eventually the US intends to create a fleet of 2,443 F-35s that will cost the state some $1.3 trillion.

Countries like Britain, Canada, Italy and Turkey are funding the F-35 development and hope to get new aircraft once they’re fully ready.

“The cost overruns on this are stunning,” Maloof said. “One person I’ve spoken to about the F-35 has said it’s so bad and so serious…that our allies may actually resort to other capabilities because they now lack air superiority.”

Maloof concluded that the Pentagon could switch from development of the ill-fated F-35 program that hasn’t met the initial expectations to the alternatives like development of mass destruction weapons.