Grey zone attacks ‘bring war to our doorstep’, MPs warn as UK told to toughen defences
The line between war and peace is being deliberately erased by hostile states, MPs have warned, as the UK is urged to urgently boost its defences against a wave of "grey zone" attacks that threaten national stability.
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Britain is underprepared for this wave of hostile activity from states like Russia and China operating just below the threshold of all out war.
A new report from Parliament’s Defence Committee says the UK’s military and critical infrastructure remain dangerously vulnerable to so-called “grey zone” threats – including cyberattacks, sabotage, disinformation, and the covert use of criminal and proxy actors to disrupt society.
The vulnerabilities of liberal democracies like the UK are laid bare in the report. Open societies and interconnected digital economies make them particularly susceptible to disinformation and cyber threats. Free access to media and the internet enables the rapid spread of propaganda, while political competition and a lack of cohesive strategy can hinder effective responses.
Much of the UK’s critical infrastructure, being privately owned, is at heightened risk from both cyber and physical attacks.
The MPs say hostile states are now targeting Britain with increasing frequency, sophistication and scale – and warn the government has been slow to adapt.
“Our adversaries have purposefully blurred the line between peace and war," said Committee Chair Tan Dhesi MP. "
"Grey zone threats pose a particularly insidious challenge – they unsettle the fabric of our day-to-day lives and undermine our ability to respond," he added.
The committee heard evidence that Russia remains the most aggressive actor, with one former MI6 chief warning the Kremlin sees itself “at war with the West”. China, by contrast, was described as pursuing “textbook” political interference, but without the same open hostility.
Grey zone threats include attacks on undersea internet and energy cables, ransomware campaigns, and weaponising immigration flows.
For the UK, grey zone attacks include the potential disruption or destruction of around 60 undersea data and energy cables and numerous energy pipelines surrounding the British Isles.
The stakes are stark: “Disrupting or destroying data cables or energy pipelines could have devastating consequences for the UK,” the committee warns, referencing the 2022 Shetland cable outage—which was accidental, not hostile—but still “led to pretty much widespread panic”.
While the armed forces can play a deterrent role, the report argues that grey zone threats “usually require a cross-government—and even a whole of society—approach”, involving not just the military but also intelligence agencies, police, the judiciary and civil society.
The Ministry of Defence does have some assets adapted to this murky domain, including:
- 77th Brigade, which conducts information operations to influence adversaries’ will and understanding;
- The Ranger Regiment, deployed in high-threat environments to work with partner nations; and
- RFA Proteus, a specialist vessel brought into service in 2023 to protect critical undersea infrastructure.
But these capabilities are “extremely limited”, the report says. The 77th Brigade is under-recruited, information operations lack clear career pathways, and RFA Proteus—though welcome—is a converted civilian ship, not suited to continuous or wartime seabed protection.
The government originally called for at least two undersea surveillance ships, but only one has entered service. “RFA Proteus is a single vessel and therefore unable to provide continuous seabed protection across multiple areas,” the report notes, adding that this could even impact the safety of Britain’s nuclear deterrent submarines.
Evidence of Russian underwater sensors found in UK waters has raised alarm, and when asked if Moscow was behind it, the Russian ambassador said, “I am not going to deny it.”
By contrast, the United States has deployed specially modified nuclear-powered submarines to operate on the seabed—and is already preparing their next generation.
Among the report’s key recommendations are calls for expanded defence capabilities, enhanced cyber resilience, deeper partnerships with allies, a whole-of-government approach, and increased public engagement.
The Committee concludes that while the UK is increasing defence spending to 2.5% of GDP by 2027, this must not come at the expense of countering grey zone threats.
A balanced investment is deemed essential to deter and defeat both conventional and unconventional attacks, ensuring the UK’s security in an era where the line between peace and war is increasingly blurred