UK to Hold Largest Home Defence Exercise in Decades to Test Hybrid Attack Readiness

By Sebastian Wigg, Alice Charalambous and Alexandra Ryabov

The UK government has announced Operation Albiston Shadow, its largest home defence exercise in decades, to be held in 2027 to test the country's ability to counter hybrid threats, including cyberattacks, sabotage of critical infrastructure, and disinformation campaigns. The multi-day exercise, revealed as part of the Annual Statement on National Resilience, will run alongside a wider Nato exercise and involve ministers and hundreds of officials from across government and the public sector, though the precise scenario remains classified. It comes alongside a wider modernisation effort, with the UK updating its classified crisis response plans, known as the "War Books," for the first time since 2004 under the Home Defence Programme.

The exercise reflects a broader shift in UK threat assessment, driven by rising Russian naval activity near British waters, ongoing instability from the war in Ukraine, and tensions in the Middle East. Testing government and public sector readiness at this scale, and doing so publicly, signals an attempt to demonstrate deterrence as much as to improve capability, treating resilience to hybrid attack as a visible extension of conventional defence posture rather than a separate domain. The decision to update crisis planning frameworks untouched for over two decades suggests officials assess that the pace and coordination of hybrid threats have outstripped existing structures, and that closing that gap is now viewed as urgent enough to warrant the country's most significant home defence rehearsal in a generation.