The Ukraine War - also referred to as the Russo-Ukrainian War in its broader context - is an ongoing armed conflict between Russia and Ukraine that has its origins in the post-Soviet geopolitical realignment of Eastern Europe. The conflict has two principal phases: a first phase beginning in February 2014 with Russia's annexation of Crimea and the outbreak of separatist fighting in the Donbas region of eastern Ukraine, and a second, dramatically escalated phase beginning on 24 February 2022 when Russia launched a large-scale invasion of Ukraine across multiple fronts. The war has become the largest conventional military conflict in Europe since World War II, drawing in NATO member states as arms suppliers and economic backers of Ukraine, and prompting sweeping Western sanctions against Russia. As of 2025, active combat continues along a contested front line running through eastern and southern Ukraine.
Ukraine declared independence from the Soviet Union on 24 August 1991. The country's subsequent history was marked by competing political orientations - toward European integration on one side and maintenance of close ties with Russia on the other. A pivotal moment came in late 2013 and early 2014, when mass protests in Kyiv (the Euromaidan or Revolution of Dignity) led to the ouster of President Viktor Yanukovych, who had suspended an EU association agreement. Russia, which had maintained a naval base at Sevastopol under treaty, moved to annex Crimea in March 2014 following a disputed referendum, an action not recognized as legitimate by Ukraine, the United States, the European Union, or the United Nations General Assembly. Simultaneously, armed separatist movements emerged in the Donetsk and Luhansk oblasts, with Russia providing varying levels of political, material, and military support. The Minsk I and Minsk II agreements (2014-2015) established a ceasefire framework that reduced but did not end the fighting. See Ukraine War - History for a full account of the conflict's development from 1991 to the present.
On 24 February 2022, Russian forces crossed into Ukraine from the north (via Belarus toward Kyiv), the east (from Russia into the Donbas), and the south (from Crimea). Russian forces failed to capture Kyiv and withdrew from the north by early April 2022. Subsequent Russian operations concentrated on the Donbas and southern Ukraine. Russia formally annexed the Donetsk, Luhansk, Zaporizhzhia, and Kherson oblasts in September 2022, though it does not fully control any of them. Ukraine conducted significant counteroffensives in the Kharkiv region (autumn 2022) and partially in Kherson (November 2022), retaking substantial territory. Fighting has since largely stabilized into attritional trench warfare along a roughly 1,000-kilometer front. In August 2024, Ukraine launched a cross-border incursion into Russia's Kursk Oblast, marking the first foreign occupation of Russian territory since World War II. Casualty figures from all parties are disputed; independent estimates place combined military losses in the hundreds of thousands, with substantial civilian casualties and mass displacement. See Ukraine War - History.
The United States, United Kingdom, European Union member states, and other nations have provided Ukraine with weapons, ammunition, intelligence support, and financial aid totaling hundreds of billions of dollars. NATO as an alliance has not directly intervened militarily, though individual member states supply equipment and training. Russia has received material support from Iran (drones) and North Korea (artillery ammunition and personnel, reported from late 2024). China has maintained formal neutrality while deepening economic ties with Russia. Debate exists over the adequacy, scope, and risks of Western military aid. The war has prompted Finland and Sweden to seek and obtain NATO membership. The United Nations General Assembly has passed multiple non-binding resolutions condemning the invasion, with significant blocs of nations abstaining.
Multiple rounds of negotiations took place in the early weeks of the invasion (March-April 2022) without producing an agreement. A draft framework reportedly reached in Istanbul in April 2022 was not concluded; the reasons for its failure are disputed, with competing accounts centering on Russian bad faith and on external pressure on Ukraine to continue fighting. Since then, no formal peace talks between Russia and Ukraine have taken place. Switzerland hosted a peace summit in June 2024 attended by Ukraine and roughly 90 countries; Russia was not invited and China did not attend. Various neutral parties - including Turkey, Israel, and others - have offered mediation. The United States under President Trump (beginning January 2025) has engaged more directly in push for negotiations; the terms and conditions acceptable to each party remain unresolved. The question of whether and on what terms the war should end is actively contested. See Ukraine War - Debate.
The origins, causes, and appropriate responses to the war are subjects of substantial disagreement. Interpretive disputes include the role of NATO expansion in provoking or enabling the conflict, the legitimacy of the 2014 change of government in Ukraine, the character of Russian strategic aims (limited territorial revision vs. broader imperial reconstitution), the legal and moral status of Western arms supply, and whether negotiated territorial concessions would constitute necessary pragmatism or impermissible appeasement. See Ukraine War - Debate and the Viewpoints section below.
Some factual claims regarding the conflict are subject to international legal and scholarly consensus. The United Nations General Assembly, the International Court of Justice, and the majority of international law scholars hold that Russia's annexation of Crimea (2014) and the four oblasts (2022) violated international law and the UN Charter's prohibition on acquiring territory by force. See Ukraine War - International Law Consensus.
Consensus on causation, moral responsibility, and policy response is substantially narrower. Significant scholarly and policy disagreement exists on questions of NATO responsibility, Western policy failures, and optimal conflict resolution. These viewpoints are addressed separately.