Ukrainian forces have battled Russian invaders on three sides after Moscow unleashed the biggest attack on a European state since World War II, prompting tens of thousands of people to flee their homes.
After Russian President Vladimir Putin declared war in a pre-dawn televised address, explosions and gunfire were heard through the day in Ukraine's capital and elsewhere in the country, with at least 70 people reported killed.
The assault brought a calamitous end to weeks of fruitless diplomatic efforts by Western leaders to avert war over Russian.
"This is a premeditated attack," US President Joe Biden said at the White House on Thursday as he unveiled harsh new sanctions, co-ordinated with allies, against Russian banks, oligarchs and state companies.
"Putin is the aggressor. Putin chose this war. And now he and his country will bear the consequences."
In his address, Putin said he had ordered "a special military operation" to protect people, including Russian citizens, subjected to "genocide" in Ukraine - an accusation the West calls baseless propaganda.
"And for this we will strive for the demilitarisation and denazification of Ukraine," Putin said.
After nightfall, a picture emerged of fierce fighting across multiple fronts. President Volodymyr Zelenskiy late on Thursday ordered a general mobilisation, to be carried out within 90 days, "to ensure the defence of the state".
The Ukrainian presidential office said Russian forces had captured the Chernobyl former nuclear power plant, north of Kyiv. The plant is along the shortest route from the Ukrainian capital to Belarus, where Moscow has staged troops.
There was also fighting at Hostomel airport, just outside Kyiv, where Russian paratroopers landed. A Ukrainian official later said the airfield had been recaptured, while a senior US defence official said Russian forces were advancing closer to Kyiv.
Heavy exchanges were also reported in the regions of Sumy and Kharkiv in the northeast and Kherson in the south.
The UN refugee agency said an estimated 100,000 Ukrainians had fled their homes. Thousands were crossing into neighbouring countries such as Romania, Moldova, Poland and Hungary.
Some 57 people were killed and 169 were wounded on Thursday, Ukraine's health minister said, while the interior ministry said 13 border guards died when a Russian vessel shelled Ukraine's Zmiinyi Island, south of the Black Sea port of Odessa.
The day began with missiles raining down on targets across Ukraine and reports of troops and armour pouring across the borders from Russia and Belarus.
Putin, after referring earlier in his speech to Russia's powerful nuclear arsenal, warned: "Whoever tries to hinder us ... should know that Russia's response will be immediate. And it will lead you to such consequences that you have never encountered in your history."
Foreign Minister Jean-Yves Le Drian said the threat was indeed understood as a use of nuclear weapons, adding Putin should also understand that NATO was a nuclear alliance.
Biden has ruled out sending US troops to defend Ukraine, but Washington has reinforced its NATO allies in the region with extra troops and planes.
After consulting with the G7, Biden announced measures to impede Russia's ability to do business in the world's major currencies, along with sanctions against banks and state-owned enterprises.
Britain also targeted banks, as well as members of Putin's inner circle. European Union leaders said measures would include freezing Russian assets.
China, however, refused to describe Russia's actions as an "invasion".
Putin said he did not plan an occupation, only to disarm Ukraine and purge it of nationalists, and his endgame remains unclear.
A democratic nation of 44 million people, Ukraine voted for independence at the fall of the Soviet Union and has stepped up efforts to join NATO and the European Union, aspirations that infuriate Moscow.
Putin, who denied for months that he was planning an invasion, has called Ukraine an artificial construct - a characterisation Ukrainians see as an attempt to erase their more than 1000-year history.
There was also some dissent in Russia. Police detained more than 1600 taking part in anti-war rallies in 53 cities and authorities threatened to block media reports carrying "false information".
Other protests against Russia's invasion were held around the world.
© RAW 2022