Along with its staggering $1.5 trillion price tag, the F-35 programme has been savagely criticised by everyone from defence analysts to the current US president for a plethora of glitches and perceived design flaws which continue to plague the jet years after it began to be deployed into various branches of the US military in 2015.

The F-35 Lightning II Joint Strike Fighter is the single most problematic defence project being developed for the US military, Business Insider Pentagon correspondent Ryan Pickerell has concluded.

Citing the programme's various problems, including premature production issues, "ballooning costs, delivery delays and numerous technical challenges, among other issues," the contributor pointed out that well over two years after the Trump administration was briefed on the fighter jet's various problems, the plane continues to suffer from a swathe of reliability and parts availability problems.

Last month, the Government Accountability Office calculated that between May and November of last year, only 27 per cent of the F-35 aircraft in the US military's arsenal were fully mission capable during the period, while nearly 30 per cent of the planes were unable to fly entirely due to parts shortages.

Earlier, the Project on Government Oversight, another US watchdog, complained that the F-35 variant for the US Navy was nowhere near operational status, unprepared "to face current or future threats" and potentially dangerous for personnel operating the jets.

Other projects which made Business Insider's list of troubled defence projects included the Zumwalt-class 'stealth' destroyer, the Littoral Combat Ship, the Ford-class aircraft carrier and the electromagnetic naval railgun platform, with each of these systems said to be plagued with cost overruns, technological challenges, deployment delays, and even concerns as to whether the systems are even necessary.

The F-35 is the single most expensive weapons programme in history, with an estimated lifetime price tag of $1.5 trillion over its project 55-year lifespan, with a plethora of glitches and design problems stemming from the Pentagon's attempts to create a one-size-fits-all fighter platform to replace its fourth generation fighters.

The US plans to buy a total of over 2,600 F-35s for the air force, navy and marine corps, with some 380 planes built as of April 2019. In addition to the US, the planes have been ordered by multiple US allies, including the UK, Australia, Israel, Italy, the Netherlands, Norway, South Korea and Japan.

In April, a Japan Air Self-Defence Force F-35A crashed during a routine training flight, with its pilot presumed to have been killed. This week, the Japanese military reported finally discovering sections of the plane's wing and engine after weeks of searching. Despite the crash, and concerns that a sea-based power like Japan needs a two-engined fighter jet in case of emergencies at sea, Tokyo has vowed to continue with its planned purchase of a total of 105 F-35As for over one trillion yen ($9.1 billion).