Invasions of Ukraine

On 24 February 2022, Russia invaded Ukraine, starting the largest and deadliest war in Europe since World War II, in a major escalation of the existing war between the two countries that began when Russia attacked Ukraine in 2014. The fighting has caused hundreds of thousands of military casualties and tens of thousands of Ukrainian civilian casualties. As of April 2026, Russian troops occupy roughly 20% of Ukraine. From a population of 41 million, about 8 million Ukrainians have been internally displaced and 6–7 million have fled the country, creating Europe's largest refugee crisis since World War II.

The Russo-Ukrainian war began in February 2014 and is ongoing. Following Ukraine's Revolution of Dignity, Russia occupied Crimea and annexed it from Ukraine. It then supported Russian separatist armed groups who started a war in the eastern Donbas region against Ukraine's military. In 2018, Ukraine declared the region to be occupied by Russia. The first eight years of conflict also involved naval incidents and cyberwarfare. In February 2022, Russia launched a full-scale invasion of Ukraine and began occupying more of the country, starting the current phase of the war, the biggest conflict in Europe since World War II. The war has resulted in a refugee crisis and hundreds of thousands of deaths.

invasion of Soviet Union by Nazi German-led Axis powers in Europe

1223 Mongol military campaign in Europe

1918–1919 conflict between the Second Polish Republic and West Ukrainian People's Republic

1939 military conflict

military invasion of the Russian SFSR in Ukraine in 1919