It is with a heavy heart that the United Kingdom must now reckon with sustained confrontation from modern revisionist powers—some far larger than itself, some far more underhanded. The ‘grey zone’ of warfare has been stretched in scope and in potential for tenacity; tensions rise unreconciled by any commensurate appetite for escalation, while technological advance invites hostile innovation. The Russian state, in particular, enjoys a prolific abuse of offensive action in the respective domains of sabotage, espionage, interdiction, information and proxy. A just and considerable response may include the action in kind, where it meets strategic ends. The question of whether there exists the political will to operate incautiously belongs to the grey zone itself. What can be examined, however, is the nature of capacity.
The unconventional means of the British state are indeed expansive. Espionage is a domain in which the intelligence apparatus is, and has long been, well-equipped to operate. The relevant organisations—including MI5, MI6, GCHQ, and even elements of HM Treasury—trace their successes to the First and Second World Wars. They are globally respected, yet, paradoxically, nebulous in what activities they are respected for. Their historical feats, lasting longevity, and contemporary integration within international frameworks such as Five Eyes nonetheless suggest a vast measure of latent capability, reinforced by a disclosed intelligence account (budget) of £4.6 billion for 2025/26.
The operational mandate of foreign-facing agencies such as GCHQ and MI6 lends credence to their ultimate capacity to use these means more offensively than might otherwise be assumed. The Intelligence Services Act 1994 describes the nature of their operation—under Section 1, MI6 is given broad powers to act abroad in the interests of “national security” and “economic wellbeing” as well as “in support of the prevention or detection of serious crime”. In practice, Russia’s conduct engages all three categories, though—advantageously—their practical qualification rests on executive assessment rather than judicial determination, precisely informing agility of response. In other words, MI6 can act unconstrained upon whatever their perception. That assessment is laid bare in the Integrated Review 2023, the British government’s statement on national security policy, which recognises Russia as an “acute threat” and the perpetrator of an “illegal invasion”.
With both capability and mandate, it is therefore assured significant capacity for offensive espionage. MI6, classically concerned with human intelligence, would underpin relevant activity inside Russia; GCHQ augmenting with complementary signals intelligence. The capabilities of both agencies plausibly allow for coherent, deniable, and effectual systemic disruption and degradation of the Russian state. At the very top of the pyramid, this could entail not only mapping fractures in loyalty, but weaponising them through a targeted combination of carrot and stick—incentivising defection, backchanneling, incompetence, and conspiracy. Among the military and civil establishment, unruly figures like the late Yevgeny Prigozhin—former Wagner head and mastermind of the march on Moscow—are hardly exclusive. After years of war and repression, resentment grows, and so do elite divisions.
At the bottom of the pyramid, opportunities present to influence regional power structures and catalyse separatism. Russia is an unnatural monster, forged through conquest and coercion, less so consent. The many nations that make up Russia can be placed across vast axes of geography, culture, and economy—the common denominator is, more than anything else, unrest. Add to the sentiment the disproportionate effect of war stresses, and British agencies appear well-placed to capitalise on these grievances to undermine state cohesion, with means available for the funding—even arming—of radical elements, or the capture and direction of key figureheads. The most militant nations, Chechnya and Dagestan, offer fertile ground; their current leadership is personalised and loyal but artificial and contested. In practice, opportunistic actors of any background can be instrumentalised, with local access itself yielding operational potential well beyond espionage.
Sabotage is one such domain, and arguably the most reliable offensive action in the modern grey zone. Innovations in both military and civilian technology have made clear new theatres of conflict—the prophylaxis to which is not clear. Ukraine’s Operation Spiderweb innovated to extraordinary saboteurial effect, planting cheap remote-controlled drones deep inside Russia via local actors before coordinating their release and live-flying them into the Russian strategic bomber fleet. Moscow throws the other way, flying drones into NATO airspace, probing air defences and steering hysteria—ostensibly in the grey zone. The implementation is provocative, but British capacity provides for analogous action on a smaller scale and to more strategic ends. Drones, used sparingly and deniably—with local access—offer a risk-averse means of intruding into contested airspace and disrupting military or civilian infrastructure. Outright destruction is but one item on the menu. Such operations simply hinge on the recruitment of opportunistic on-the-ground actors; their requisite abilities often amount to little more than a low-level proficiency in modern commercial technologies.
The range of sabotage extends even further, spanning a spectrum wider than has ever been seen before. With relatively high confidence of attribution and little effective reprisal, Russia has targeted critical infrastructure of energy, transport, and communications functions. The new theatres are, notably, as much above as they are below—subsea cables and gas pipelines have become recurrent targets of this war in the grey, often victimised by civilian-flagged vessels. British naval forces demonstrate substantial capability to act similarly offensively; strategic avenues, however, remain sparse. This reflects not a lack of opportunity—targets paint seas White and Black—but the escalatory sensitivity of the naval theatre in particular. Escalation is always a risk in a security context, but here it most squarely dominates considerations, blunting nominal capacity. Theoretically, underwater drones could provide symmetrical deniable attacks on Russian infrastructure—such are imperfect options. However, the general defensive emphasis resultant, embeds another mode of grey zone action altogether.
While Russian-linked vessels patrol and loiter around critical infrastructure, British naval forces sortie to intercept and shadow them. Such confrontation, discounting kinetic exchange, falls under the domain of interdiction. In addition to conventional interceptions, British naval reach enables effectively unlimited freedom of navigation operations. These plausibly allow for more offensive signalling under intensified conditions—those entailing a sustained close-in presence near Russian infrastructure or within its EEZ, or forceful spatial contestation around Russian warships. These manoeuvres demonstrate a measured response without crossing legal or kinetic boundaries. By extension, Russia has made standard practice of interference in satellite navigation and communications. British capacity here is comparatively asymmetric. With a sophisticated cyber ecosystem and a dedicated National Cyber Force, the state reserves the means to disrupt Russian command, control, and surveillance without visible escalation. Such operations are among the most penetrative and deniable tools of grey zone engagement, capable of inflicting both literal and figurative casualties while Russian forces act in Ukraine. An assault on the, more tangible, operational information space can be complemented by a corresponding, and envelopmental, attack on the societal information space.
Information operations complete the picture of war in the grey zone and, harnessing proxies, accumulates as the last enmeshing domain in which Britain retains capacity for legitimate offensive action. Russia’s use of disinformation and narrative-shaping have been persistent but uneven in effect. Its audiences range from domestic constituencies—western voters and political elites—to the unaligned and middling states of the Global South, each of which feeds international legitimacy, diplomatic weight, and ultimately global alignment. British influence is rather diffuse than directive, though no less impactful. The state has exceptional comparative advantages in global media and linguistic reach, assets to be operationalised by the right voices, including like-minded partners. This need not resemble crude anti-Russian propaganda, but the deliberate dissemination of select truths that amplify internal contradictions and undercut Russian legitimacy. The make-or-break, as it were, will be the ongoing battle to gain initiative on—or disarm—social media platforms. Moving offensively into this domain will nonetheless impose cumulative pressure without clear thresholds for retaliation, and relieve the already exhausted advocacy for a beleaguered ‘rules-based international order’.
The message is too important not to get right. Grey zone warfare is a consequential phenomenon, one which stands on the precipice of war and peace, but its ramifications extend beyond some abstract notion of international order. British capacity for offensive action in the grey zone could mean European capacity for peace. The conduct is questionable and risky, nevertheless available. The limiting factor is not capability, legality, or opportunity, but political willingness. Escalation has been framed as one of the primary risks associating action; so too attribution—compromised unilateral operations are liable to threaten western unity. In any case, the integration of these capacities into a coherent strategy remains a prerogative above all while the grey zone is exploited by those who wish to do us harm.