Europe had not been entirely peaceful since the defeat of Nazi Germany. The wars that followed the collapse of Yugoslavia brought sieges, ethnic cleansing and mass displacement back to the continent. NATO intervened from the air in Bosnia in 1995 and conducted a 78-day bombing campaign against the Federal Republic of Yugoslavia during the Kosovo conflict four years later.
Yet Russia’s full-scale invasion of Ukraine on 24 February 2022 represented something Europe had not experienced for generations: an attempt by one major European power to subjugate another through a vast land war.
Armored columns crossed internationally recognized borders. Cities were besieged, millions fled their homes and both sides began expending ammunition and military equipment – and suffering casualties – on a scale that many European governments had ceased to imagine.
The attack did not begin the war between Russia and Ukraine. It transformed a conflict that had already continued for eight years.
The War Europe Learned to Live With
In 2014, Russia occupied and illegally annexed Crimea before intervening in eastern Ukraine, where pro-Kremlin forces seized parts of the Donetsk and Luhansk regions. Russian citizens and Moscow-backed armed groups played prominent roles in the fighting, while the Kremlin denied that it was a direct party to the conflict.
Kyiv launched the Anti-Terrorist Operation in eastern Ukraine in April 2014. On 30 April 2018, it was formally replaced by the Joint Forces Operation.
Some observers continued to describe the violence as a civil war. Ukrainians did fight on both sides, but that label obscured the decisive role of Russian personnel, weapons, equipment and political support.
The fighting nevertheless remained largely confined to the Donbas. That allowed much of Europe to regard it as a limited conflict on the continent’s periphery.
Western governments imposed sanctions, but their broader relationship with Moscow continued. European states bought Russian energy, commercial ties survived, and Russia remained connected to much of the international financial system.
The war could be condemned without forcing Europe to reconsider the foundations of its security.
February 2022 ended that comfortable distinction.
The Nuclear Shadow
Russia’s invasion differed from the Balkan wars in one crucial respect: it was launched by a nuclear-armed permanent member of the United Nations Security Council against a neighboring state whose government it sought to overthrow.
That fact has shaped the Western response from the beginning.
NATO members have supplied Ukraine with weapons, intelligence, training and financial assistance, but the alliance has avoided entering the fighting directly. A confrontation between NATO and Russia would carry the risk of escalation between nuclear powers.
Moscow has repeatedly exploited that danger, invoking its arsenal to warn Western governments against deeper involvement.
But the nuclear threat does not arise only from the possible use of a warhead.
During the failed advance on Kyiv in 2022, Russian forces occupied the Chernobyl site and moved through its exclusion zone. Reports that soldiers had disturbed contaminated ground in the Red Forest caused alarm, although the immediate radiological consequences proved limited.
The more persistent danger surrounds the Zaporizhzhia Nuclear Power Plant, Europe’s largest nuclear facility, which has been under Russian control since March 2022.
Even with its reactors shut down, the plant requires external electricity for cooling, monitoring and other essential safety functions. Its connection to the grid has repeatedly failed, leaving it dependent at times on emergency generators. The International Atomic Energy Agency has continued to warn that the plant’s electricity supply and wider safety conditions remain precarious.
No major nuclear accident has occurred. That does not mean the danger is imaginary. It means safety systems have so far continued to function under conditions for which no civilian nuclear plant was designed.
The Human Cost
The invasion produced the fastest-growing and largest displacement crisis in Europe since the Second World War. More than six million Ukrainians sought refuge abroad, while millions more were displaced within the country.
The death toll is harder to comprehend. By the end of June 2026, the United Nations had verified at least 16,431 civilian deaths and 48,613 injuries since the full-scale invasion began, including 803 children killed and 2,960 injured. The UN has repeatedly warned that the real figures are considerably higher, particularly because deaths in occupied territory and heavily devastated cities are difficult to document.
Military losses are far harder to establish. The Center for Strategic and International Studies estimates that between February 2022 and June 2026, Russia suffered around 1.4 million troops killed, wounded or missing, including an estimated 400,000 to 450,000 deaths. Ukraine is estimated to have suffered between 525,000 and 625,000 military casualties, including 125,000 to 150,000 fatalities. Taken together, the estimates suggest that between 525,000 and 600,000 soldiers have been killed and that total military casualties on both sides have exceeded 2 million.
These figures are estimates rather than a final accounting. But even the lower bounds reveal a war whose human cost has no recent European parallel.
The consequences entered daily life across the continent. Ukrainian children arrived in schools, families required housing and governments opened labor markets and extended temporary protection. Energy prices, public spending and industrial policy became entangled with the conflict.
The invasion also exposed weaknesses accumulated during decades in which major continental warfare had appeared increasingly implausible. European governments discovered that ammunition stocks were limited, defense production could not be expanded quickly and armed forces designed for smaller missions were poorly prepared for a prolonged war of attrition.
Countries that had built their energy strategies around Russian supplies were forced to seek alternatives. Several major Russian banks were excluded from the SWIFT financial messaging system, Russian central-bank assets were immobilized and European airspace was closed to Russian aircraft.
These measures did not isolate Russia from the entire world. But the political and economic relationship that had connected it with much of Europe was broken.
The Conflict Returns to Russia
The war also became a turning point for Russia itself.
Confidence in a rapid victory was widespread among Moscow’s allies and propagandists before the attack. On 5 February 2022, less than three weeks before the invasion, Belarusian President Alexander Lukashenko told Russian television host Vladimir Solovyov: “Ukraine has no chance against our combined forces. If war breaks out, it will last three or four days. There will be no one there to fight us.”
The remark did not reveal the Russian General Staff’s formal timetable. It did, however, capture the contemptuous assumption that Ukrainian resistance would collapse almost immediately.
Russian forces advanced from Belarus toward Kyiv and attempted to overwhelm the government before it could organize an effective defense. Instead, they were forced to withdraw from northern Ukraine.
What Moscow had presented as a limited “special military operation” became a prolonged war of attrition whose effects gradually crossed back over the Russian border.
In June 2023, Wagner leader Yevgeny Prigozhin launched an armed rebellion against Russia’s military leadership. His fighters seized military facilities in Rostov-on-Don and advanced toward Moscow before abruptly turning back.
The mutiny lasted less than a day, but its significance exceeded its duration. A mercenary force armed, financed and used by the Russian state had turned against the country’s military establishment.
In August 2024, regular Ukrainian troops crossed into Russia’s Kursk region, mounting the largest cross-border offensive of the war. Ukraine also intensified attacks on military and energy infrastructure farther inside Russia, with drones reaching airfields, oil facilities and the Moscow region.
These operations are not equivalent to Russia’s invasion of Ukraine. Moscow launched a war of conquest, occupied Ukrainian territory and subjected cities across the country to sustained bombardment.
Ukraine’s attacks arose from that aggression and sought to disrupt the forces and infrastructure supporting it. They nevertheless undermined the Kremlin’s attempt to keep the conflict physically remote from Russian society.
Moscow sought to wage war abroad while preserving normality at home. Instead, Russia experienced mobilization, cross-border fighting, attacks on strategic infrastructure and the most serious armed rebellion of Vladimir Putin’s rule.
The End of an Illusion
More than four years after the full-scale invasion began, Ukraine remains independent and its government remains in power.
Russia still occupies substantial Ukrainian territory and possesses greater reserves of manpower and military equipment. Ukraine continues to suffer devastating attacks, immense economic pressure and losses that will shape the country for generations. The outcome remains uncertain.
What is no longer in doubt is how profoundly the war has changed Europe.
Finland and Sweden abandoned decades of military non-alignment and joined NATO, expanding the alliance to 32 members. Across Europe, governments have sharply increased defense spending and sought to rebuild military stocks and industrial capacity. NATO members have committed to spending 5% of GDP on defense and security-related expenditure by 2035, while the European Union’s Readiness 2030 initiative is intended to mobilize up to €800bn ($925bn) in additional defense investment.
At the same time, the boundary between the war and NATO territory has become increasingly fragile. Russian drones and military aircraft have repeatedly violated Allied airspace. Russian drone wreckage was recovered in Romania, while a Russian Shahed crashed in Latvia in 2024. In September 2025, more than 20 Russian drones entered Polish airspace, prompting NATO aircraft to respond. Days later, Estonia said three Russian MiG-31 fighters remained inside its airspace for 12 minutes, although Moscow denied the violation.
The incidents continued in 2026. In March, a drone diverted during a Russian attack on Ukraine crossed around 4 km into Romania before crashing near Parcheș. Two months later, a Russian-made Geran-2 attack drone struck an apartment building in Galati, injuring a woman and a child. In June, NATO aircraft shot down another drone after it entered Latvian airspace. And in July, a Russian Kh-101 cruise missile landed in eastern Poland, prompting Warsaw to summon the Russian ambassador.
NATO says Russia has been testing the alliance’s resolve and responsiveness along its eastern flank for years and that such airspace violations are becoming more frequent. Europe is therefore not simply rearming in response to a theoretical future threat. The boundaries Russia is testing are already those of NATO itself.
Europe can no longer assume that borders are protected by convention alone, that trade will inevitably restrain territorial ambition or that military weakness carries no political cost.
Peace was never the continent’s natural condition. It was a political achievement sustained by alliances, deterrence and the willingness to defend the order on which European security depended.
Europe did not suffer because it believed in peace.
It suffered because it had begun to believe that peace no longer needed defending.