Something has shifted in Europe and the signs are clear. For more than three years the war in Ukraine was, for most of the continent, terrible but contained, someone else’s cities burning. In September 2026 that sense of distance has begun to collapse. Governments are telling their citizens to prepare for the possibility of war, intelligence chiefs are warning that Russia may test NATO directly within months, Baltic states are dusting off evacuation plans for hundreds of thousands of people. And over the weekend, Ukraine launched the largest drone assault of the entire war deep into Russia, a reminder that the conflict is not winding down but escalating. The question no longer being whispered but spoken aloud in European capitals is whether the war might soon stop being Ukraine’s alone.

The most visceral sign of the new mood came from London. The United Kingdom has told its citizens to start preparing for the possibility of war, advising households to stockpile canned food and drinking water, while the country’s chief of defence warned that Britain faces the most dangerous period in decades. For a nation that has not asked its population to think in these terms since the Cold War, the advice landed with a jolt.

But the UK’s gesture was not an isolated one. Even famously neutral Switzerland has adopted a new national security strategy explicitly calling for greater resilience and the ability to defend itself against armed attack, its government announcing three objectives, to strengthen resilience, improve protection and enhance defence capabilities. When Bern begins talking about defending itself, the temperature of the whole continent has changed. The warnings from those with access to intelligence have been unusually direct, starting with Polish Prime Minister, Donald Tusk, who told his parliament that assessments suggest Russia may launch drone or missile attacks on NATO territory in the coming months, and, most strikingly, that Moscow could seek to demonstrate that Article 5 of the NATO treaty, the collective-defence commitment that is the alliance’s entire foundation, is “more theoretical than practical.” He warned that Russia could engineer incidents involving drones or missiles crossing into NATO territory and then describe them as accidents, repeated provocations designed to erode confidence in the alliance without ever quite triggering a unified response. French President Emmanuel Macron called Tusk’s assessment credible and well founded, summoned France’s political leaders for a confidential intelligence briefing, and announced new measures to protect critical infrastructure from intensifying Russian hybrid attacks.

Polish and Romanian soldiers in the Suwałki Gap – an 80km stretch of the Polish-Lithuanian border between Kaliningrad and Belarus. Photograph: Wojtek Radwański/AFP/Getty Images

The alarm is grounded in a pattern of real incidents, not speculation alone. Over recent weeks Russian drones have strayed into Polish airspace in numbers without precedent, Russian fighter jets briefly entered Estonian airspace before being intercepted, and NATO aircraft have repeatedly scrambled across the Baltic to meet Russian planes flying without flight plans or radio contact. Belarus, Russia’s closest military ally, conducted large exercises this month near the Suwałki Gap, the narrow corridor connecting the Baltic states to the rest of NATO and long considered one of the alliance’s most vulnerable points. NATO’s own senior military figures have spoken openly about the danger of a Russian false-flag attack. Each incident on its own might be dismissed as an accident or a probe. Together, European officials increasingly read them as a campaign.

The logic behind the fear is what makes it serious, and it is worth stating plainly because it explains why Europe is preparing for something other than a repeat of 2022. Vladimir Putin does not need another full-scale invasion on the scale of Ukraine to challenge NATO. He can climb an escalation ladder instead: sabotage, cyberattacks, drones and missiles, and then, perhaps, a limited military operation designed to test whether NATO still means what it says. The genius and the danger of such a strategy is that it targets the alliance’s credibility rather than its territory in force. The uncomfortable question haunting European planners was captured bluntly in one analysis: would the United States under Donald Trump truly go to war with Russia over a patch of land like the Suwałki Gap? If the answer is uncertain, then deterrence itself is weakened, and an adversary may be tempted to find out.

The weekend’s events underlined that this is no abstract war-gaming. Ukraine launched a massive drone assault on Russia, with Moscow claiming its air defences shot down more than 1,600 drones since Saturday, including 450 aimed at the capital, in what the city’s mayor called the largest drone attack on Moscow since the war began. President Volodymyr Zelensky said the strike hit a key oil facility and a military supply depot, dealing a significant blow to Russia’s war machine. The barrage came only days after Trump said Ukraine and Russia had both agreed to stop hitting energy targets, a deal Kyiv never confirmed, and it deepened the very dynamic, strikes on energy infrastructure, that has rattled global fuel markets. A war that Washington keeps describing as close to a settlement keeps, in practice, intensifying.

The practical preparations underway across the continent are perhaps the clearest measure of how seriously governments are taking the threat. The Baltic states have coordinated plans for potentially moving hundreds of thousands of people living close to the Russian and Belarusian borders, with evacuation corridors mapped from Vilnius toward Poland. Poland has revised its evacuation plans for war and other emergencies, including arrangements for vulnerable populations. Finland has folded guidance on drone threats and air-raid alerts into its national preparedness system, and runs civil-defence drills simulating cyberattacks, sabotage, infrastructure failures and missile strikes. Latvia has strengthened its eastern border, expanded its drone and counter-drone capabilities and launched a new frontier security operation. NATO has held exercises near the strategically vital Swedish island of Gotland. This is not the vocabulary of a continent at peace. It is clearly the infrastructure of one preparing, methodically, for the possibility that it is not.

And yet, precisely because the alarm is so loud, it is also important to include the voices urging caution, because they come from the people arguably closest to the threat. Security officials in the three Baltic states, which border Russia and would be first in any confrontation, have taken a notably more measured view. Normunds Mežviets, director of Latvia’s State Security Service, said officials had seen no indications of an imminent attack, even as he acknowledged signs that Moscow was preparing for more decisive action in Europe, and noted it remained unclear whether those preparations reflected concrete operational plans or a broader effort to spread fear and uncertainty in Western societies. Estonia’s Jonatan Vseviov criticised what he called a panicked social-media discussion of a possible Russian invasion. The Baltic reasoning is instructive: Russia’s military remains heavily committed in Ukraine, and excessive public talk of imminent war risks doing the Kremlin’s work for it, sowing exactly the anxiety and economic disruption that hybrid warfare is designed to produce.

That tension, between urgent warning and deliberate calm, is the truest picture of where Europe stands. Both positions can be correct at once. Russia can be genuinely preparing to test NATO over the coming years while no specific invasion is imminent this autumn. The danger can be real and the panic can still be counterproductive. Indeed, several intelligence officials made precisely this double point: that a campaign against NATO could intensify in months rather than years, and that public panic would nonetheless play directly into Kremlin psychological operations. The task facing European governments is the delicate one of preparing their societies without terrifying them, of building resilience without manufacturing the very fear the adversary seeks to spread.

What is beyond dispute is that a threshold has been crossed in how Europe thinks about its own security. The estimates converge on a window of danger, with Polish and NATO assessments pointing toward 2027 as the point at which Russia, possibly in concert with China, could be strong enough to seek a broader confrontation, German officials citing 2029, and the European Union aiming to be able to repel a Russian attack by 2030.

Whichever date proves closest, the shared assumption is new and sobering: that the question is no longer purely whether Ukraine can be helped to survive, but whether the rest of Europe is ready to defend itself. For a continent that spent the decades after the Cold War treating large-scale war as a memory, that is a profound and unsettling shift. Europe is not at war beyond Ukraine, but, for the first time in a generation, it is seriously preparing for the possibility that it could be, and that preparation, whatever else it signifies, is itself the measure of how much the world has changed.