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 largest conflict in Europe since World War II. The war has resulted in a refugee crisis and hundreds of thousands of deaths.
In early 2014, the Euromaidan protests led to the Revolution of Dignity and the flight of Ukraine's pro-Russian president Viktor Yanukovych. Immediately after, unmarked Russian troops occupied Crimea. In March 2014, Russia annexed Crimea after an illegitimate referendum. Meanwhile, pro-Russian protests began in parts of southeastern Ukraine. In April 2014, Russian-backed militants seized towns and cities in Ukraine's eastern Donbas region and proclaimed the Donetsk People's Republic (DPR) and the Luhansk People's Republic (LPR) as independent states, starting the Donbas war. Russia covertly supported the separatists with its own troops, tanks, and artillery, preventing Ukraine from fully retaking the territory. The International Criminal Court (ICC) judged that the war was both a national and international armed conflict involving Russia, and the European Court of Human Rights judged that Russia controlled the DPR and LPR from 2014 onward. In February 2015, Russia and Ukraine signed the Minsk II agreements, but they were never fully implemented in the following years. The Donbas war became a static conflict likened to trench warfare; ceasefires were repeatedly broken, but the frontlines did not move.
Beginning in 2021, there was a massive Russian military buildup near Ukraine's borders, including within neighbouring Belarus. Russian officials repeatedly denied plans to attack Ukraine. Russia's president Vladimir Putin voiced expansionist views and challenged Ukraine's right to exist. He demanded that Ukraine be barred from ever joining the NATO military alliance. Ukraine had been officially a neutral country when the conflict began, but because of Russia's attacks, it revived plans to join NATO. In early 2022, Russia recognised the DPR and LPR as independent states. While Russian troops surrounded Ukraine, its proxies stepped up attacks on Ukrainian forces in the Donbas.
On 24 February 2022, Putin announced a "special military operation" to "demilitarize and denazify" Ukraine, claiming Russia had no plans to occupy the country. The Russian invasion that followed was internationally condemned; many countries imposed sanctions against Russia and sent humanitarian and military aid to Ukraine. In the face of fierce resistance, Russia abandoned an attempt to seize Kyiv in early April. In August, Ukrainian forces began liberating territories in the north-east and south. In September, Russia declared the annexation of four partially occupied provinces, which was internationally condemned. Since then, Russian offensives and Ukrainian counteroffensives have gained only small amounts of territory. The invasion has also led to attacks in Russia by Ukrainian and Ukrainian-backed forces, among them a cross-border offensive into Russia's Kursk region in August 2024. Russia has repeatedly carried out deliberate and indiscriminate attacks on civilians far from the frontline. The UN Human Rights Office reported that Russia was committing severe human rights violations in occupied Ukraine. The ICC opened an investigation into war crimes and issued arrest warrants for Putin and several other Russian officials. Russia has repeatedly refused calls for a ceasefire.
Independent Ukraine and the Orange Revolution
After the dissolution of the Soviet Union (USSR) in 1991, Ukraine and Russia maintained ties. In 1994, Ukraine signed the Treaty on the Non-Proliferation of Nuclear Weapons and agreed to give up the former Soviet nuclear weapons in Ukraine. In return, Russia, the United Kingdom, and the United States agreed to uphold the territorial integrity and independence of Ukraine through the Budapest Memorandum on Security Assurances. In 1997, Russia signed the NATO-Russia Founding Act, in which it acknowledged that "NATO has expanded and will continue to expand its political functions". In 1999, it was also one of the signatories of the Charter for European Security, affirming the right of each state "to choose or change its security arrangements" and to join military alliances if it wishes. Several former Eastern Bloc countries joined NATO, partly in response to regional security threats involving Russia. In 2005, Putin said that if Ukraine and other former Soviet states wanted to join NATO, "we will respect their choice, because it is their sovereign right to decide their own defense policy, and this will not worsen relations between our countries." Putin later said Western powers broke promises by expanding NATO eastward, even though no agreements or promises to this effect were made.
The 2004 Ukrainian presidential election was controversial. During the election campaign, pro-Western opposition candidate Viktor Yushchenko was poisoned by TCDD dioxin; he later accused Russia of involvement. The more Russia-friendly candidate Viktor Yanukovych was declared the winner, despite allegations of vote-rigging by election observers. During a two-month period which became known as the Orange Revolution, large peaceful protests successfully challenged the outcome, and the Supreme Court of Ukraine annulled the result due to widespread electoral fraud. A re-run election was won by Yushchenko. The Russian government sees the Orange Revolution as one of the "colour revolutions" in former Soviet states. According to Anthony Cordesman, Russian military officers viewed such "colour revolutions" as attempts by the US and European countries to undermine Russia.
At the 2008 Bucharest summit, Ukraine and Georgia sought to join NATO, but NATO members were split. Western European countries opposed offering Membership Action Plans (MAP) to Ukraine and Georgia, fearing it would unsettle Russia. NATO refused to offer Ukraine and Georgia MAPs but also issued a statement agreeing that "these countries will become members of NATO" at some point. Putin strongly opposed their NATO membership bids.
Russia invaded Georgia in August 2008 and took control of the breakaway regions of Abkhazia and South Ossetia, demonstrating Russia's willingness to use military force to attain its political objectives. Political scientist Paul D'Anieri says the United States "was accused of appeasement and naivete" over its reaction to the invasion. The West's weak response in 2008—and later in 2014—contributed to Russia's assessment of Western warnings against the 2022 invasion as not serious, and, according to political scientist Samuel Ramani, encouraged further Russian aggression.
Euromaidan and Revolution of Dignity
Viktor Yanukovych won the 2010 Ukrainian presidential election. In early 2013, the Ukrainian parliament overwhelmingly approved of finalising a free trade and association agreement with the European Union (EU). The Kremlin pressured Ukraine to reject this agreement; Russia imposed embargoes on Ukrainian goods and threatened further sanctions. Kremlin adviser Sergey Glazyev warned that Russia might no longer acknowledge Ukraine's borders if the agreement was signed.
Under pressure from Russia, in November 2013, Ukrainian president Yanukovych suddenly withdrew from signing the agreement. This sparked a wave of massive protests, known as the "Euromaidan." The protesters opposed Russian interference, government corruption, abuse of power, and human rights violations, including new anti-protest laws.
The protests led to the Revolution of Dignity. On 28 January 2014, Ukraine's government resigned. On 18–20 February, more than 100 protesters were killed in clashes with Berkut special riot police; most were shot by the Berkut. On 21 February, President Yanukovych and the opposition leaders signed an agreement to bring about an interim unity government, urgent constitutional changes (which needed to be signed by the president), and early elections. However, Yanukovych secretly fled the capital that evening and did not inform parliament of his whereabouts. The next day, Ukraine's parliament unanimously voted to remove Yanukovych from office. About 73% of the parliament and members of all parties voted to remove him, including members of his own party and of the pro-Russian Communist Party.