Russian forces launch a full-scale assault on Ukraine, with its military attacking the country from the north, east and south
Ukrainian President Zelensky says 137 Ukrainian citizens - both soldiers and civilians - died on Thursday
People in the capital, Kyiv, and elsewhere are trying to flee - some 100,000 have left so far, the UN says
There are also renewed reports of explosions in the port city of Mariupol, home to half a million people
Russians seize control of the Chernobyl complex - site of the world's worst nuclear disaster
UK and US announce fresh new sanctions on Russia, including asset freezes on banks
President Vladimir Putin defends his move, saying there was no other way to defend Russia
But US President Joe Biden says Putin's aggression will cost Russia dearly
Biden says he has no intention of fighting with Russia - but vows to defend every inch of Nato territory.
He adds that you do not need blood unless you intend starting a war - referring to reports that Russia had been stocking up on blood supplies near the border with Ukraine.
Image source, Getty ImagesBiden says he's announcing the first tranche of sanctions against Russia.
He announces sanctions on sovereign debt.
Biden says that means cutting off the Russian government from Western finances.
"It can no longer raise money from the West," Biden says.
He says the US will continue to "escalate sanctions" if Russia continues to escalate its actions in Ukraine.
President Biden says that he has authorised the additional movement of US forces to allies in Eastern Europe.
In his speech, Biden said that the forces and equipment - which are already in Europe - will be sent to the Baltic countries of Estonia, Latvia and Lithuania.
"Let me be clear, these are defensive moves on our part," he said. "We have no intention of fighting Russia".
The deployments, Biden added, are meant to send a message to US allies that it will defend Nato territory and abide by its treaty commitments.
Biden says the US will work with Germany to ensure the Nord Stream 2 pipeline "will not move forward".
Russia will pay an even steeper price if it continues aggression - including steeper sanctions, he warns.
Joe Biden asks what "gives [Putin] the right to declare new so-called countries on territory that belongs to his neighbours?"
This is a "flagrant violation of international law", the US President says.
President Biden said he believes that Putin is setting up "a rationale" to go much further and take more Ukrainian territory by force.
"This is the beginning of a Russian invasion of Ukraine," he said, referencing Putin's speech on Monday and the Duma authorisation to send troops into the Donbas.
Image source, White HousePresident Biden, speaking at the White House, says Putin "bizarrely" claimed two regions he recognised as independent states are no longer part of Ukraine.
Russia is carving out parts of Ukraine and asserted these regions extend even deeper, he says.
US President Joe Biden is beginning his address, where he's expected to announce new sanctions against Russia.
We'll bring you all the latest updates here.
Paul Adams
BBC diplomatic correspondent
Speaking earlier, the EU’s foreign policy chief, Josep Borrell, said the Kremlin’s order to deploy troops to eastern Ukraine did not represent “a fully fledged invasion".
Was it, perhaps, the “minor incursion” that Joe Biden spoke about in mid-January? That remark sent US officials into a frenzy of clarification, fearing that Biden might inadvertently have offered Vladimir Putin a green light for military action in Ukraine.
As a result, a new term was coined: “further invasion”. American and other Western officials have used it ever since.
The point being that Russia has been invading Ukraine since 2014, when it helped pro-Russian separatists to launch a war in the east.
So the threat to send in more Russian troops did not, in itself, represent a dramatic increase in the extent to which Ukraine is “invaded” (even if the rhetoric surrounding the move was deeply alarming).
Twenty-four hours later, it’s still not clear if any additional Russian forces have entered the two “people’s republics” of Donetsk and Luhansk. It’s also not clear what they will do when - of if - they get there.
Each territory occupies a portion of the “oblasts” (administrative regions) of Donetsk and Luhansk. If Russia were to try to push the boundaries of each, then this would certainly represent a “further invasion".
Image source, Getty ImagesLloyd Austin welcomes Dmytro Kuleba to the Pentagon
US defence secretary Lloyd Austin says Vladimir Putin can still change course and avoid war.
Speaking at the Pentagon, ahead of a meeting with Ukrainian Foreign Minister Dmytro Kuleba, Austin says the US is in "lockstep" with its allies "to try find a way to avoid further conflict".
"Mr Putin can still avoid a full blown, tragic war of choice," Austin adds.
Austin says the "latest invasion" of Ukraine threatens the "peace and security and prosperity of Ukraine, and of the trans-Atlantic community".
More now on those EU sanctions on Russia after its decision to recognise the separatist-controlled areas of eastern Ukraine.
The EU's foreign policy chief, Josep Borrell, told a news conference in Paris that the sanctions “will hurt Russia - and will hurt a lot".
The sanctions were agreed unanimously by EU Ministers, in strong co-ordination with the US, the UK, and Canada, Borrell said.
The EU says the sanctions will target 351 MPs who voted for recognition, and the 11 who proposed it, as well as 27 individuals and entities who are "playing a role in undermining Ukraine’s sovereignties".
This includes, according to Borrell:
"Speak plainly!"
Putin had some strong words for the head of Russia's Foreign Intelligence Service during a meeting with top security officials on Monday.
US President Joe Biden's expected update on the situation in Ukraine at the White House has now been postponed to around 14:00 EST (19:00 GMT).
The reason for the delay isn't clear.
Biden is expected to make significant announcements during his address, including new economic sanctions against Russia.
With journalists all over the world reporting on the situation in Ukraine, one reporter in particular has attracted attention on social media today.
Luxembourg-based Associated Press journalist Philip Crowther has gone viral on Twitter after posting a video showing off his language skills.
The video contains a compilation of his reports on Ukraine in no less than six different languages.
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US President Joe Biden's address is running a bit late.
When it starts you can watch his speech on the stream at the top of this page.
Just press the play button at the top of your screen, next to our main headline.
More now on those European Union measures against Russia, which Ursula von der Leyen, the president of the European Commission, has also been speaking about.
The bloc announced sanctions against Russian individuals and entities connected with the decision to recognise the separatist-controlled areas of Eastern Ukraine.
They include measures hitting MPs in Moscow's lower house of parliament who voted for the recognition. They'll also target Russian banks, and the ability of the Russian state to access the EU's financial markets.
Von der Leyen said the measures would be wide ranging, and tough.
"We will make it as difficult as possible for the Kremlin to pursue its aggressive actions," she said.
Germany was "absolutely right" to put on hold a major gas pipeline project from Russia, she added.
"This crisis shows that Europe is still too dependant on Russian gas, we have to diversify our supplies," she said.
"Our action is today is a response to Russia's aggressive behaviour. If Russia continues to escalate this crisis that it created we are ready to take further action in response."
We're waiting for US President Joe Biden, who is due to address the nation at 13:00 EST (18:00 GMT).
He is expected to announce the first of what could be many levels of new sanctions and export controls against Russia.
It's a response to Moscow's decision to recognise two breakaway regions of Ukraine as independent and send troops there.
Western countries have already started to impose sanctions - the UK has hit five banks and three wealthy individuals with restrictions.
Russia has made a decision to evacuate its diplomatic staff from Ukraine, its foreign ministry says.
"Our first priority is to take care of Russian diplomats and employees of the embassy and consulates general," it says in a statement, adding that this will begin "in the very near future."
Reality Check
Image source, EPAIn the House of Commons this afternoon, Boris Johnson was asked about whether Roman Abramovich, the Russian billionaire owner of Chelsea Football Club in England, would be facing sanctions.
The prime minister replied that “Abramovich is already facing sanctions”.
Labour MP Chris Bryant later told MPs: “I don’t think Abramovich has been sanctioned”.
Mr Abramovich is not listed on the searchable database, external provided by the UK Office of Financial Sanctions Implementation.
The prime minister's official spokesman later told reporters Johnson "misspoke" when he told the Commons that Abramovich was facing sanctions.
Image source, Getty ImagesEU ministers have unanimously agreed new sanctions against Russia to target 27 individuals and entities who undermine Ukrainian integrity, the EU's high representative for Foreign Affairs says.
Josep Borrell tells a news conference Russian lawmakers will be targeted for backing the recognition of two rebel-held regions in eastern Ukraine, as well as banks financing Russian decision-makers and operations in those territories.
The ability of the Russian state and government to access EU capital, financial markets and services will be affected, he says.
However, he says sanctions will only be one part of the bloc's response.