Russian President Vladimir Putin launched a full-scale invasion of Ukraine on Thursday, unleashing air strikes and ordering ground troops across the border in fighting that Ukrainian authorities said left dozens of people dead.
The attack triggered Western warnings of unprecedented sanctions against Russia as NATO, European Union (EU) and G7 leaders condemned the invasion and vowed to hold Moscow accountable.
Weeks of intense diplomacy failed to deter Putin, who massed over 150,000 troops on Ukraine's borders in what the West said was the biggest military build-up in Europe since World War II.
"I have decided to proceed with a special military operation," Putin said in a televised address before dawn on Thursday.
Shortly afterwards, the first bombardments were heard in Ukraine's capital, Kyiv, and several other cities, according to AFP correspondents.
Russian air strikes hit military installations across the country as ground forces moved in from the north, south and east, forcing many Ukrainians to flee their homes to the sounds of bombing.
Olena Kurilo was among 20 wounded after a blast sent shards of glass from her windows into her face in the eastern Ukrainian town of Chuguiv.
"Never, under any conditions will I submit to Putin. It is better to die," the 52-year-old teacher said, her face swathed in bandages.
Ukrainian President Volodymyr Zelensky said there was now a "new iron curtain" between Russia and the rest of the world, like in the Cold War.
United States (US) President Joe Biden vowed to "hold Russia accountable" and G7 leaders said Putin was on the "wrong side of history" after a virtual summit.
"This crisis is a serious threat to the rules-based international order, with ramifications well beyond Europe," the G7 leaders said in a statement.
Biden was expected to give a speech at 1730 GMT.
Attack On Chernobyl
Across Ukraine, at least 68 people were killed, including both soldiers and civilians, according to an AFP tally from Ukrainian official sources.
Air raid sirens sounded over Kyiv at the break of dawn after the city's main airport was hit in the first bombing of the city since World War II.
The city declared an overnight curfew but said underground stations would remain open throughout the to serve as bomb shelters.
Ukraine said that Russian forces had managed to capture an airfield near Kyiv and fighting was also raging around Chernobyl in northern Ukraine – the site of a nuclear disaster.
"Russian occupying forces are trying to take over the Chernobyl Nuclear Power Plant. Our soldiers are giving their lives so that the tragedy of 1986 does not happen again," Zelensky wrote on Twitter.
He called the attack on Chernobyl – a vast area that has been abandoned since the disaster because of continued high levels of radioactivity – "a declaration of war on all of Europe".
In the deadliest single strike reported by Ukrainian authorities, 18 people were killed at a military base near the Black Sea port of Odessa.
Ukraine's emergency services also said a military plane with 14 people on board crashed south of Kyiv and that they were determining how many people died.
As the assault began, Zelensky declared martial law and accused Russia of acting like "Nazi Germany" – but asked people not to panic and promised victory.
Ukrainian forces said they had killed "around 50 Russian occupiers" while repulsing an attack on a town on the frontline with Moscow-backed rebels, a toll that could not immediately be confirmed by AFP.
'Feel Sorry For Everyone'
In the eastern Ukrainian town of Chuguiv, a son wept over the body of his father among the wreckage of a missile strike in a residential district.
"I told him to leave," the man said repeatedly, sobbing next to the twisted ruins of a car.
On the Russian side of the border, in Pokrovskoye, there was an eerie calm and no sign of the soldiers who had filled the village on Wednesday.
Anastasia Yashonkova came out of a store where she bought small toys and a lemonade for her four-year-old son.
"This is really scary," said the 30-year-old. "I feel sorry for everyone."
'Significant Economic Risk'
Russia's defence ministry said it had destroyed over 70 military targets, including 11 airfields.
Ukraine said Russian tanks and heavy equipment crossed the border in several northern regions, in the east as well as from the Kremlin-annexed peninsula of Crimea in the south.
The fighting spooked global financial markets, with stocks plunging and oil prices soaring past US$100.
European wheat prices also hit a record high on expectations of lower supplies as Ukraine and Russia are two of the world's biggest producers.
International Monetary Fund (IMF) chief Kristalina Georgieva said the fighting carried "significant economic risk" for the world.
'Harshest Sanctions'
In his televised address, Putin justified the assault as a defence of the self-proclaimed Donetsk and Lugansk republics in eastern Ukraine.
The Kremlin earlier said the leaders of the two separatist territories had asked Moscow for military help against Kyiv after Putin recognised their independence on Monday.
A conflict between the separatists and government forces has dragged on since 2014, killing more than 14,000 people on both sides.
"Putin's aim is to end the existence of Ukraine as it was yesterday," said Tatyana Stanovaya, a non-resident scholar at the Carnegie Moscow Center.
"I cannot see anything that would stop Russia now".
In Brussels, EU foreign policy chief Josep Borrell said Russia would be hit with the "harshest sanctions" the EU has ever imposed.
The Organization for Security and Co-operation in Europe’s (OSCE) acting chairman, Polish Foreign Minister Zbigniew Rau, said the invasion was a "crime against humanity".
NATO said it had activated "defence plans" for allied countries but alliance chief Jens Stoltenberg said there were no plans to send NATO forces into Ukraine.
Russia has long demanded that Ukraine be forbidden from ever joining NATO and that US troops pull out from Eastern Europe.
The Russian invasion rattled eastern NATO members once dominated by Moscow, with several calling for a strong response from the military alliance.
Poland said it would open nine reception centres along its border with Ukraine in anticipation of an influx of refugees.
In the Baltics, Lithuania declared a national emergency and Latvia banned three Russian TV channels that were broadcasting in the country, saying they posted a "threat to national security".
Demonstrators took to the streets of European capitals to condemn Russia but a small anti-war protest in Moscow was quickly shut down by police and dozens of people were detained.