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
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President Joe Biden and German Chancellor Olaf Scholz have both said that cutting Russia off from the global banking system, Swift, is not being proposed right now.
But what would happen if it was?
Excluding Russia from Swift would risk severe repercussions for banks that are owed money - either now or in the longer term.
This is particularly true in Germany, which has deep financial ties with Russia and feels it has done its share of economic sacrifice by suspending certification of the Nord Stream 2 pipeline.
Although being de-Swifted would be disruptive for Russia, there is an alternate system - called CFPS - that Russia set up after it annexed Crimea in 2014. Similarly, China has also set up a secondary system, CIPS.
Expelling Russia would probably only push it closer to China and play into the hands of the Xi administration, which is keen to "de-dollarise" the world's financial architecture. This would accelerate that trend and ambition.
Ukrainian President Volodymyr Zelensky reportedly just said "the enemy has designated me as the target number one, and my family as the target number two".
In a video address carried by Ukrainian media, Zelensky says he is staying in the capital Kyiv's "government quarters" and his family is also in Ukraine. He did not provide further details.
Zelensky also warns that Ukrainian officials now have "information that enemy sabotage groups have entered Kyiv".
The president did not elaborate on what those groups might be.
Image source, EPAMore on the situation at Chernobyl tonight: White House press secretary Jen Psaki just told reporters at her daily briefing that there are reports Russian soldiers are holding the staff of the Ukrainian nuclear site hostage.
"We are outraged by credible reports that Russian soldiers are currently holding the staff of the Chernobyl facilities hostage," she said.
"This unlawful and dangerous hostage-taking, which could upend the routine civil service efforts required to maintain and protect the nuclear waste facilities, is obviously incredibly alarming and gravely concerning.
"We condemn it and we request their release."
British Prime Minister Boris Johnson told his government on Thursday evening that Ukrainian soldiers have been putting up a fight, tweets the BBC's political correspondent Iain Watson.
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Image source, Getty ImagesRussian forces have taken control of Chernobyl, site of the 1986 nuclear disaster and a place that remains radioactive to this day - prompting significant concern from international nuclear watchdogs.
Prof Claire Corkhill, nuclear materials expert at Sheffield University, told the BBC about the dangers of military clashes taking place near the site.
“This is not a place to have ammunition flying around," she said.
The Chernobyl site contains several nuclear waste containment facilities - including the “new safe confinement” - the protective dome that covers the reactor that was so badly damaged by the infamous 1986 explosion.
“These buildings are designed to keep radioactive materials inside, but they’re not necessarily armoured; they’re not designed to operate in a war zone,” she said.
Prof Corkhill said that although piercing one of these structures wouldn’t necessarily cause a repeat of the Chernobyl disaster - where plumes of radioactive material dispersed across Europe - it could “set us back 30 years in terms of the work that has been done clearing up the site”.
It could release and disperse radioactive material in the local area, she said.
Chris Morris
BBC Reality Check
Image source, Getty ImagesThe Nord Stream 2 pipeline that would bring gas to Germany has shuttered amid the latest fighting
There was plenty of criticism that Western sanctions in the days leading up to this invasion did not go far enough, fast enough.
These new measures will hit the Russian economy much harder. But there are still potential gaps.
UK Prime Minister Boris Johnson said sanctions against major Russian banks include one of the largest state banks, VTB, which will have all its assets frozen. But another major bank, Sberbank, was not mentioned.
And the Ukrainian government wanted more – in particular moves to disconnect Russia from the international payment system known as Swift, which thousands of banks use to exchange information.
The US and the UK are in favour of such a move, but some European countries fear it could damage their own banks.
Suspending Russia from Swift is still under consideration, but the hesitation is a reminder that in a globalised world all sanctions tend to have an impact on the countries imposing them as well.
And the real trouble with sanctions is that they don’t work quickly.
They do increase pressure, and they can do damage.
But the international community is not trying to damage the Russian economy just for the sake of doing so.
It wants economic pressure to force a change in Putin’s political and military calculations.
Meanwhile, the invasion of Ukraine continues.
Ukrainian President Volodymyr Zelensky has just signed a decree ordering a general mobilisation.
All Ukrainians who can carry arms have been urged to defend their homeland.
The country's conscripts and reservists are also being called up, according to the decree, which is to be in effect for 90 days.
Ukrainian President Volodymyr Zelensky says 137 Ukrainian citizens - both soldiers and civilians - died on Thursday, the first day of a massive Russian military assault.
Gordon Corera
Security correspondent, BBC News
The head of Britain's MI6 has tweeted about intelligence on Ukraine.
“US and UK intelligence communities uncovered Putin’s plans for Ukraine. We exposed his attempts to engineer ‘false flag’, fake attacks to justify his invasion. We revealed his plans to assassinate Ukrainian leaders and senior officials,” Richard Moore, also known as "C", said in a tweet.
“This attack was long planned, unprovoked, cruel aggression. No amount of Russian disinformation will now disguise that fact from the international community," wrote the Secret Intelligence Service chief.
US and UK intelligence seem to have had an unusual and highly accurate level of insight into Putin’s plans and strategy.
The unprecedented publicising of some of that intelligence has had tactical success in partly disrupting Putin’s plans - including for provocations and false flags.
It may have also helped draw Western countries closer together. But even this level of insight couldn’t provide a way of stopping or deterring him.
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Image source, ReutersLong queues have been seen at bus and train station in the capital Kyiv, as people have been desperately trying to go western regions of Ukraine
All Ukrainian men aged between 18 to 60 are now banned from leaving the country, Ukraine's state border guard service (DPSA) says.
It adds the measure is aimed at "guaranteeing Ukraine's defence and the organisation of timely mobilisation".
The temporary ban will remain in force for the duration of martial law declared on Thursday morning.
Steve Rosenberg
BBC Moscow Correspondent
I think Vladimir Putin is fuelled by resentment at how the Cold War ended, with the West declaring victory and Russia losing power, influence and territory.
I think he's also motivated by an almost semi-religious belief that Ukraine must be with Russia, must be in Russia's orbit, and Russia as a great power has the right to its own sphere of influence. I also think he has disdain for the West and Western leaders, whom he deems weak and disunited.
What can the West do about this? It’s very difficult to say. I think the Kremlin would've factored in sanctions. The Kremlin will know that the US will not put boots on the ground in Ukraine. The West does not want a war with Russia and Russia knows that.
But I would say this. If you’ve been in power for 22 years, as Putin has, you start to feel invincible, you start to think you can’t put a foot wrong, that you’re Teflon. And that's when mistakes start to creep in.
Just from speaking to people on the streets and witnessing the strength of feeling against this offensive, I wonder whether this Russian invasion will turn out to be Putin's fatal error.
Image source, Oksana PotapovaCountless city residents are hunkered in subways to avoid potential fighting
Countless Kyiv residents are sleeping in underground metro stations as midnight approaches in Ukraine.
The people - some of whom have brought their pets, extension cords and even air mattresses - are mostly calm, according to one evacuee.
The place is "not too crowded, most people are scrolling their phones, trying to catch the latest news", says Oksana Potapova.
"We seem settled enough to spend the night here," she wrote on Facebook.
"And given the news about heavy fighting near Kyiv, the takeover of Chernobyl power plant, and forecasts of possible attacks on Kyiv, it seems like a good decision."
Image source, Oksana Potapova
Image source, Oksana Potapova
Paul Adams
BBC diplomatic correspondent
A new iron curtain is falling across Europe.
That’s what this country’s beleaguered president, Volodymyr Zelensky, said in his most recent televised statement.
The echoes of Winston Churchill’s famous 1946 speech in Fulton, Missouri were powerful.
“From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent,” Churchill told his audience back then.
Today’s iron curtain has moved eastwards, meandering from the Gulf of Finland, around Belarus and along Ukraine’s eastern border and on down to the Black Sea.
That, Zelensky says, is where it should stay, with Ukraine firmly on the west.
But that conviction feels like a fragile, disappearing dream tonight, as Russian armour cuts deep into Ukrainian territory, with the prospect of worse to come.
With savage ferocity, Vladimir Putin has reached out, grabbed Ukraine by the scruff of the neck and is trying, by force of arms, to drag this hopeful nation back across the fence.
Night has fallen and a curfew is in effect in Kyiv after the first full day of Russia's invasion of Ukraine. If you're just joining us, or catching up on events, here's what's been going on:
If you want more detail, you can read our guide to the conflict, and how it has unfolded today, by clicking here.
Ilya Barabanov
BBC Russian Service, Kyiv
Image source, AFP via Getty ImagesSmoke rises in the background as people walk down a street near the airfield
All day long the Russian troops have been trying to take over an airfield at Hostomel, on the northern outskirts of the Ukrainian capital.
This airfield is of strategic importance: if captured it could become a springboard for the Russian army into Kyiv.
Judging from verified videos, at least two Russian helicopters were shot down over it. Journalists from CNN filmed a group of Russian paratroopers landing there while the Bellingcat investigative website said it had intelligence that 18 war planes with reinforcements were heading towards it from Russia.
Later in the evening it became clear that a heavy battle for Hostomel was raging and Ukrainian forces were using both airstrikes and artillery.
By 11pm Kyiv time (21:00 GMT) an official statement was released, saying that the airfield was back in the Ukrainian hands.
Image source, Getty ImagesA protester is detained in Saint Petersburg
More than 1,700 people have been arrested during anti-war protests across dozens of cities in Russia, an independent monitor reports.
More than 900 were arrested in Moscow and over 400 in Saint Petersburg, according to OVD-Info, which tracks arrests at opposition rallies.
Thousands gathered near Pushkin Square in central Moscow, while up to 1,000 people gathered in the former imperial capital Saint Petersburg, the AFP news agency reports.
Image source, Getty ImagesMany held Ukrainian flags in Moscow
"No to war" was spray-painted on the front gate of the Russian parliament's lower house.
"I am in shock. My relatives and loved ones live in Ukraine," Anastasia Nestulya, 23, told AFP in Moscow.
"What can I tell them over the phone? You hang in there?"
Image source, ReutersNavalny (standing) while on trial from prison
Jailed Russian opposition leader Alexei Navalny - on trial in a Moscow prison - has accused Vladimir Putin of using the invasion of Ukraine to cover up Russian corruption.
In a video published by independent news outlet Dozhd, Navalny is heard expressing his opposition to the invasion of Ukraine.
Wearing a prison uniform, he says it would lead to a "huge number of victims, destroyed futures and the continuation of this line of impoverishment of the citizens of Russia".
Quote MessageThis war between Russia and Ukraine was unleashed to cover up the theft from Russian citizens and divert their attention from problems that exist inside the country.
Alexei Navalny
Navalny has been jailed for over a year on old fraud charges, after surviving a poison attack, which he and the West say was carried out by the Kremlin.
He is being tried inside the maximum security prison on new charges that could see his imprisonment extended by a decade.
Vladimir Putin has spoken by phone to French President Emmanuel Macron and given him an "exhaustive" explanation of the reasons for Russia's actions in Ukraine, the Kremlin says.
Macron requested the call and they agreed to stay in contact, the Kremlin says.
In France, the Elysee Palace says Macron spoke first to Ukraine's President Zelensky. He then spoke to President Putin and demanded an end to military operations and warned of massive sanctions.
The French president has attempted to avert a Russian invasion in recent weeks, including holding talks with Putin in the Kremlin.
Imogen Foulkes
BBC News, Geneva
Image source, ReutersThe UN Refugee Agency warned today of a rapidly deteriorating situation in Ukraine as people flee their homes looking for safety.
UN High Commissioner for Refugees, Filippo Grandi, warned "the humanitarian consequences on civilian populations will be devastating. There are no winners in war but countless lives will be torn apart".
The refugee agency is calling on Ukraine’s neighbours to keep their borders open to those fleeing and says it stands ready to "support efforts by all to respond to any situation of forced displacement".
Meanwhile, the president of the International Committee of the Red Cross, Peter Maurer, called on those fighting to respect international law, and to ensure civilians were protected.
The UN had already issued a record appeal for funding in 2022 to relieve crises in Syria, Yemen, Afghanistan, and the drought-ridden Sahel region in Africa. A further major conflict and refugee crisis in the middle of Europe could stretch its resources well beyond their limits.