The U.S. Air Force is moving ahead with a $4.2 billion infrastructure programme for its UK network, led by new hardening and support works at RAF Lakenheath and targeted upgrades at Menwith Hill, Mildenhall and Fairford. The package also carries $1.3 billion in draft projects, signalling a longer pipeline for secure hangars, bunkers, command-and-control space, housing and special operations support across American-operated sites. Lakenheath takes the largest share, with works tied to reinforced sheltering and security around the F-35A force, while Menwith Hill gets $163 million for intelligence and missile-warning infrastructure. The build-out deepens the UK’s role in U.S. nuclear, ISR and expeditionary posture.