The NAO report reveals that only £11 billion has been spent so far, but full delivery of the first 48 aircraft remains behind schedule. The program's scope has since grown to a planned 138 jets, with cost estimates now including £14 billion in long-term support needs—such as fuel, infrastructure, and personnel.

Gareth Davies, head of the NAO, warned that the UK is not yet realizing the full strategic benefits of the fifth-generation fleet. “The F-35 program offers significantly improved capability and considerable economic benefits to the UK. But the capability benefits are not being fully realized due to delays, infrastructure gaps and personnel shortages,” Davies said.

In response, the Ministry of Defence confirmed it would have two combat-ready squadrons by the end of 2025 and emphasized that the program remains within its approved budget. The MoD also noted plans to acquire 12 cheaper A-model jets, instead of the B variant, to reduce unit cost by 25% and contribute to NATO’s nuclear deterrence missions.

NATO Demands Drive Expansion

The report comes as NATO allies face growing pressure from Washington to increase defense spending amid fears of further Russian aggression in Europe. Britain’s F-35 expansion is part of a broader strategic shift to strengthen alliance capabilities.

However, the decision to equip the US-built aircraft with UK-developed missiles has been delayed until the next decade, raising concerns about operational effectiveness. The NAO cautioned that these continued delays are “undermining the armed forces’ war-fighting capability.”

Despite budgetary control claims, the audit paints a picture of a program struggling to meet its potential without further prioritization and resourcing.