Grey-zone warfare, also known as hybrid warfare, describes hostile acts that occupy a hazy space between untroubled peace and open war. They encompass everything from drone surveillance and straying fighter jets to cyber-attacks, sabotage of critical infrastructure and the planting of explosive parcels. The term describes a "defender's dilemma", as Elisabeth Braw of the Atlantic Council puts it: respond harshly and you appear to overreact; let it pass and you lose credibility; retaliate in the grey zone and you instigate "a race to the bottom".
Since Russia's full-scale invasion of Ukraine in February 2022, its intelligence services have led a campaign of sabotage and subversion across Europe. Research by the International Institute for Strategic Studies found that incidents of confirmed Russian sabotage against European infrastructure more than tripled between 2023 and 2024. Tactics include drones over Poland, MiG fighters traversing Estonian airspace, telecom cables damaged beneath the Baltic Sea, airports paralysed by cyber-attacks and quadcopters, mysterious explosions and assassinations, and bot swarms pumping out propaganda to disrupt elections.
Russia's tactics appear aimed in part at countries most helpful to Ukraine and at sapping public confidence in Western governments' ability to protect their citizens. Boris Bondarev, a former Russian diplomat who resigned to protest against the invasion, says Russia hopes to distract NATO countries from supporting Ukraine by forcing them to focus on their own rearmament. As Friedrich Merz, Germany's chancellor, put it: "We are not at war, but we are no longer at peace, either."
Vladimir Putin's grey-zone campaign against NATO pursues three aims. First, to break the unity of the alliance—making Europeans doubt each other and in particular question America's commitment, with the ultimate goal of prising America away from Europe altogether. Second, to raise the cost to European countries that support Ukraine's army: Poland, Estonia and Denmark have suffered drone incursions, GPS jamming and sabotage; Germany has faced cyber-attacks on its defence and logistics firms; Moldova and Romania have had their elections interfered with—in both cases unsuccessfully. Third, to discredit liberal democracies whose wealth and resilience show up his failures. Russia's GDP is smaller than Italy's even though its population is well over twice as large.
The world's shadow fleet—ships that conceal themselves or their identities—has soared from about 200 vessels in 2022 to roughly 1,000, now making up 19% of the global oil-tanker fleet. North Korea pioneered the tactic of "going dark" by turning off automatic identifier signals; Iran and Venezuela followed suit before the practice "went on steroids" after Russia's invasion of Ukraine. Shadow vessels are used for sanctions-busting, espionage and sabotage, blurring the line between criminality and state-directed hostility. In the Baltic Sea, NATO's Baltic Sentry mission patrols for threats to undersea cables and pipelines; Estonia has passed a law authorising its navy to attack civilian vessels damaging critical infrastructure. See also: Russia, shadow fleet.
China's grey-zone tactics differ from Russia's in several respects. The gradual encirclement of Taiwan with ever bolder and more frequent military exercises appears intended to sap the morale of ordinary Taiwanese and make the island's eventual absorption seem inevitable. China also has considerable economic clout to influence its neighbours. Chinese leaders speak of mastering zhanzheng kongzhi, or "war control"—an approach to escalation management that emphasises patience and discipline. As Tong Zhao of the Carnegie Endowment for International Peace notes, China is not "heavily influenced by what Russia is doing"; if it makes a move on Taiwan or in the South China Sea, it will do so on its own initiative. As Michael Mazarr of the RAND Corporation observes, "The Chinese leadership feel like history is moving in their direction already, and they're not quite as paranoid and anxious to lash out. Russia is in the domain of losses and feels it has to take some big risks." Chinese ships have also damaged undersea cables and a gas pipeline in the Baltic Sea by dragging their anchors.
No-one would remember the Good Samaritan if he had only had good intentions. He had money as well.