Here is a timeline of the main events since the Russian invasion of Ukraine two years ago.
The war has killed or wounded hundreds of thousands of people, according to Western estimates.
- February 2022: invasion -
Russian President Vladimir Putin announces a "special military operation" in Ukraine on February 24, saying he wants to demilitarise and "de-Nazify" the country.
A full-scale invasion starts, with missile strikes on Ukrainian cities sparking the worst refugee crisis in Europe since World War II.
The West imposes unprecedented sanctions on Russia. The European Union and United States send Ukraine light weapons and aid.
Ukraine pushes back Russian forces from Kyiv. Moscow makes gains in the south, seizing in March the city of Kherson, close to the Moscow-annexed Crimea peninsula.
- War crimes revealed -
In early April, AFP discovers the bodies of at least 20 civilians lying on a street in the Kyiv suburb of Bucha, the first of a string of discoveries in towns that Russian forces had occupied which spark an international outcry and war crimes investigations.
- Mariupol falls -
On May 21, Russia announces the fall of the southeastern port city of Mariupol, which had been relentlessly bombed, after the last Ukrainian troops holding out at a steelworks surrender.
- Ukraine hits back -
Kyiv launches a major offensive to retake Kherson as a bitter battle begins for the eastern town of Bakhmut, spearheaded on the Russian side by the Wagner mercenary group.
Ukraine retakes hundreds of towns and villages in a lightning counter-offensive around Kharkiv.
On September 30 Putin formally annexes the Ukrainian regions of Lugansk, Donetsk, Kherson and Zaporizhzhia.
On October 8, an explosion causes major damage to a bridge linking Crimea to the Russian mainland.
Putin blames Ukrainian secret services for the attack.
Russian forces retaliate by striking Ukraine's energy infrastructure.
On November 9, as Ukrainian forces advance, Moscow orders its troops to retreat from Kherson, marking a stunning defeat in one of the regions it annexed.
- Tanks on the way -
On January 25, 2023 Germany finally agrees to send Ukraine some of its powerful Leopard tanks.
The United States follows, announcing that it will provide 31 Abrams tanks. On May 19, President Joe Biden authorises the delivery of F-16 fighter jets to Kyiv.
In April, Ukraine also receives anti-missile Patriot defence systems from Washington.
After months of bloody fighting, Russian forces seize the war-battered town of Bakhmut in May.
In June a long-awaited Ukrainian counter-offensive begins.
- June 24: Wagner rebellion -
Wagner chief Yevgeny Prigozhin leads a mutiny to bring down Moscow's top brass.
Prigozhin, who had threatened to march on Moscow, announces a pull-back following mediation via Belarus's leader Alexander Lukashenko.
Prigozhin dies two months later in a plane crash, with speculation in Ukraine and the West that the Kremlin orchestrated the accident.
- August: grain corridor -
Ukraine sets up a grain corridor to link its ports to the Bosphorus Strait, several weeks after Russia refuses to agree on a new accord to allow cereal exports through the contested Black Sea.
- February 2024: fall of Avdiivka -
Russian forces on February 17 capture the eastern industrial town of Avdiivka after an onslaught which began in October.
Over the following weeks Russia claims new gains in eastern Ukraine.
Kyiv responds to ongoing attacks on its energy infrastructure by targeting refineries and military sites on Russian soil.
- April: US aid package -
After a months-long delay in the US Congress, the Senate on April 23 approves a $61 billion aid package for Ukraine.
Biden vows to sign the bill quickly and send weapons "this week".