Image source, Anadolu Agency via Getty Images

That's all from us for now on this complex and fast-developing story - thanks for staying with us!

We've tried to answer as many of your questions as possible - huge thanks go to Paul Adams, the BBC's International Affairs Correspondent who has recently returned from reporting in Ukraine, and Steve Rosenberg, our correspondent in Moscow.

You can still get all the latest developments on this and other major news stories - on the BBC News website.

This page was edited by Jasmine Taylor-Coleman and Kevin Ponniah. Our reporting crew were Chris Giles and Yaroslav Lukov.

Paul Adams
BBC International Affairs Correspondent

We're going to be wrapping up this Q&A shortly but we can't leave you without answering this - Is Russia preparing to invade Ukraine?

The only honest answer any of us can give right now is that we have absolutely no idea. Russia has certainly assembled enough men and equipment to do something in Ukraine. Not enough (by a mile) for a full scale invasion, but enough, perhaps, to mount a more limited operation - perhaps in the Donbas.

But Russians are not clamouring for war and Putin knows that "victory" in Ukraine could kill an awful lot of his own soldiers.

Does his visceral distaste for the very idea of Ukraine trump all other rational considerations? Surely not. But he's caught the West's attention and he has a long list of demands which go way beyond the question of Ukraine and Nato (particularly as he knows Ukraine is not about to join).

So he will continue to hold a gun against Ukraine's head while he pursues his wider agenda. And as any film buff will tell you, when there's a gun on the table, it usually means someone's going to use it later.

Why is Nato expanding?published at 16:23 Greenwich Mean Time 21 January 2022

16:23 GMT 21 January 2022

Paul Adams
BBC International Affairs Correspondent

Kate, 35, Washington in the US, asks why doesn’t Nato agree to sign a written agreement that Ukraine will not join the military alliance?

It's true that Nato has expanded eastwards, though not since 2004, when the Baltic republics of Latvia, Lithuania and Estonia joined, along with Romania, Bulgaria, Slovakia and Slovenia.

Others have joined since, but Albania, Croatia, Montenegro and North Macedonia did not represent a further expansion eastwards.

All joined because they wanted to be part of a security alliance that tied them to Europe and America.

Some had been part of the old Warsaw Pact, which no longer existed. They no longer wanted to be part of a Russian sphere of influence (and Russia, preoccupied with its own domestic concerns, wasn't in a position to persuade them otherwise).

Nato has what it calls an "open door" policy. Anyone can apply to join. Nato will not go against its own principles and tell aspiring countries that they are no longer welcome.

But it's no secret that membership is not currently on the cards for Ukraine (for fairly obvious reasons). President Biden said as much on Wednesday.

Image source, EPA

Steve Rosenberg
BBC Moscow Correspondent

Image source, RIA NOVOSTI/AFP via Getty Images

This has a lot to do with history… and geopolitics.

Both Russia and Ukraine trace their roots back to Kievan Rus, way back in the 9th Century. It’s why many Russians feel such a close connection to their Ukrainian neighbours.

In time Ukraine became part of the Tsarist empire and, later, the Soviet Union.

Many here think Vladimir Putin is on an historic mission to force Ukraine back into the fold, back into Russia’s sphere of influence.

This is a president who famously told President Bush that “Ukraine isn’t a real country”.

Last year, Putin wrote that “Russians and Ukrainians are one people, a single whole”.

The Kremlin can’t abide the thought of Ukraine tilting West, embracing European institutions, western democracy and - one day - joining Nato.

Losing Ukraine would be a blow to Russia’s perception of itself as a great power.

If you're just joining us, welcome. There's been a lot to take in as we answer your questions on the escalating tensions between Russia and Ukraine. So let's recap on the main points today:

‘Frank’ talks: The US and Russian met to discuss Ukraine in Geneva, with further discussions expected in the coming weeks.

Russian forces: There are fears that a huge Russian military force assembled near Ukraine's borders will be used to invade.

New sanctions threat: The US and its allies have threatened new sanctions, while Russia itself denies planning to attack, despite an estimated 100,000 Russian troops deployed near Ukraine.

Our correspondents Paul Adams and Steve Rosenberg have been helping to guide you through the complexities of what’s happening.

Vitaliy Shevchenko
BBC Monitoring

Image source, UKRAINA TV

There is a lot of apprehension in Ukraine about the possibility of a fresh Russian invasion, and there are hopes that talks between Russia and the West will be able to avert it.

"Escalation or diplomacy?" wondered one presenter of the daytime news bulletin on Ukraine's popular 1+1 TV channel.

As US Secretary of State Antony Blinken was meeting Russian Foreign Minister Sergei Lavrov in Geneva, the presenter said: "Washington is trying to find out whether the Kremlin will dare to launch a wide-ranging attack on Ukraine."

In a sign of how jittery the situation is, some Ukrainians this morning thought that such an attack has already started. Reporting about a minor earthquake, Ukraina TV said "people thought the bombing has begun".

The prospect of an all-out war with Russia is real for journalists in Ukraine. One of them, Yuri Butusov, has analysed whether Russian tanks will be able to reach the Ukrainian capital Kyiv "within two hours" as suggested by some social media users.

His prediction is that while it is true that Russia has more firepower, "Ukraine has what it takes to meet the enemy and prevent a Russian blitzkrieg".

Steve Rosenberg
BBC Moscow Correspondent

Image source, Reuters

In 1994, Russia signed a document that became known as the Budapest Memorandum.

Among other things, it committed Moscow to respecting the independence, sovereignty and the existing borders of Ukraine after it got rid of its Soviet-era nuclear weapons.

But 20 years later Russia invaded Ukraine, annexing Crimea and fomenting a war in eastern Ukraine.

Why can't Russia just join Nato?published at 15:54 Greenwich Mean Time 21 January 2022

15:54 GMT 21 January 2022

Steve Rosenberg
BBC Moscow Correspondent

Michel in Canada asks if Putin is worried about Ukraine joining Nato, why doesn't the West invite Russia to join the alliance?

It seems unthinkable now, but the idea of Russia joining Nato was something that crossed Vladimir Putin's mind twenty years ago. It never worked out.

Some people think that after the end of the Cold War, a brand new European security system – including Russia – should have been created.

Nato would argue that the alliance isn't the problem and rather that it's Russian aggression that threatens European security.

Image source, EPA

What do people in Russia think about Ukraine tension?published at 15:45 Greenwich Mean Time 21 January 2022

15:45 GMT 21 January 2022

Steve Rosenberg
BBC Moscow Correspondent

Viktor asks what is the community in Russia’s reaction to the demands of Putin, and what is the main narrative of the local news outlets in Russia?

My local newspaper vendor Valentina tells me her customers are talking a lot about the tension and the danger of conflict.

“People are wishing each other good health and no war!” she says.

As for the state media, it’s been denying that Russia plans to invade Ukraine, dismissing Western “hysteria” and accusing Nato of threatening Russia’s security.

Paul Adams
BBC International Affairs Correspondent

Steve answered a question a little earlier about whether Russia is afraid of Nato. He is right that Russia doesn't really fear Nato, but they do resent it.

I travelled to Moscow with a Nato delegation in the mid-2000s. The delegation thought it was engaged in outreach but I sensed their Russian military hosts were suspicious. And when the Nato side started to talk about all the great work they were going to do in Afghanistan, I could see veterans of Russia's own, painful experience there bristling.

For all the (many) toasts to brotherhood and co-operation, I think the Russians felt patronised by Nato. At the time, Russia was still smarting from its spectacular loss of global influence and Putin had yet to turn this around. It left a lasting impression on me.

What could Russia do to Europe's gas supplies?published at 15:34 Greenwich Mean Time 21 January 2022

15:34 GMT 21 January 2022

Steve Rosenberg
BBC Moscow Correspondent

George, a reader, asks if the West should be concerned that if Russia does invade and is hit with new sanctions, could they choke off gas supplies?

It’s a possibility. Russia likes to portray itself as a reliable energy supplier. But in a sanctions war the energy gloves might come off.

The EU relies on Russia for 40% of its gas. So any supply reduction or cuts by Russia would be felt acutely in Europe.

True, Russia would lose out financially, too. But the Russians think they have an alternative market - China - and are already looking to boost energy supplies there.

How are people in Ukraine feeling?published at 15:27 Greenwich Mean Time 21 January 2022

15:27 GMT 21 January 2022

Paul Adams
BBC International Affairs Correspondent

I'm tempted to say "ask Danil" (see post below), as he's living this crisis day to day.

But I was in Kyiv last week and I found a mixture of apprehension and resignation. As President Zelensky says, "what's new here?" - Ukraine and Russia have been at loggerheads for eight years.

War is already a reality, even if the conflict in the Donbas is now a frozen, low-level confrontation. I didn't detect any panic in Kyiv, but people did seem to believe that one day, unless he's stopped, Vladimir Putin will try to do something.

They know where their bomb shelters are and some say they're willing to volunteer in one way or another if war breaks out. But they're really tired of the conflict and have no appetite for a fight which they know they would probably lose.

Image source, Getty Images

In the event of an invasion, how likely are civilian casualties?published at 15:22 Greenwich Mean Time 21 January 2022

15:22 GMT 21 January 2022

Paul Adams
BBC International Affairs Correspondent

Danil Gorbunov, 42, in Ukraine, asks how any military operation could be carried out - is an all-out war possible?

This could play out in any number of ways, from so-called "hybrid" attacks - hacking, disinformation, etc - all the way up to a full-scale invasion the likes of which Europe has not seen since World War Two.

One way or another, civilians will be caught up in it. They might find themselves freezing in their homes as the power grid collapses, or trapped behind Russian lines if, as some have speculated, Russian tanks move in from the territory of neighbouring Belarus (personally I find this unlikely, but Russia seems happy to keep everyone guessing).

As you know, Danil, this conflict has already claimed around 14,000 Ukrainian lives. If Russia tries to take more territory or install a more friendly regime in Kyiv, it's hard to see how this won't result in many, many casualties.

Image source, Reuters

Why does Russia fear Nato?published at 15:19 Greenwich Mean Time 21 January 2022

15:19 GMT 21 January 2022

From Mike Hancock, 54, in Pittsburgh, US

Steve Rosenberg
BBC Moscow Correspondent

I don’t believe Russian officials really fear Nato, which is a defensive alliance. According to the US secretary of state, only 6% of Russia’s borders touch Nato countries. Is that a threat to Russian national security?

Also, many Nato countries actually have good relations with Moscow; and Russia even sells weapon systems to Turkey, a Nato member. I think this is more about the Kremlin trying to carve out a sphere of influence for itself on its doorstep - and using Nato as an excuse to do that.

Our correspondents have been talking a lot about Nato. So, what is it?

The North Atlantic Treaty Organisation the world's most powerful regional defence alliance - that means members see an attack on any of them as an attack on all of them.

It was formed in 1949 to counter the threat of post-war communist expansion as the Soviet Union sought to extend its influence in Europe after World War Two.

It says its general aim is to "safeguard the freedom, common heritage and civilisation" of its members by promoting "stability and wellbeing in the North Atlantic area".

It originally consisted of 12 founding members - including the UK - and it now has 30.

Russia’s Vladimir Putin wants the alliance to abandon military exercises and stop sending weapons to eastern Europe, which Moscow sees as its backyard.

Find out more here.

Paul Adams
BBC International Affairs Correspondent

Ryan Johnston, 24, in Belfast, Northern Ireland asks: Would this story be very different if Ukraine was already a Nato member?

Ukraine (and Georgia) have been on a theoretical path to Nato membership since a summit in Bucharest in 2008. But it's a long and rocky path.

Since 2014, when Ukrainians got rid of a president they thought was going to side with Russia rather than Europe, the country has been at war with Russia.

First Russia took over Crimea. Then it encouraged pro-Russian separatists in the south-east of the country (the area called the Donbas).

Nato can't welcome members who are already involved in conflicts of this kind and there are also all sorts of other things Ukraine needs to do, in terms of political reforms, improving their military, etc.

Right now, to welcome Ukraine into Nato would be seen as the ultimate red rag to a bull (Putin). So no-one thinks it's going to happen any time soon. In many ways, this is a red herring, as Putin knows perfectly well that membership is not around the corner.

If Putin says he won't invade Ukraine, why is US warning Russia?published at 15:05 Greenwich Mean Time 21 January 2022

15:05 GMT 21 January 2022

from Asad Ullah, a PhD student at Shandong University in China

Paul Adams
BBC International Affairs Correspondent

Words are one thing (and you're right - the Russians keep saying this), but actions point in another direction.

The massing of forces, the support for separatists in the Donbas (including the handing out of around 1 million Russian passports), the threat of dire consequences if Ukraine does anything provocative (which, to now, it sensibly isn't).

Plus, Putin's rejection of Ukraine's independent identity is not a secret - he wrote a long treatise on the subject last summer. It's easy to find on the internet, but be prepared for a deep dive into ancient Russian history.

Image source, Belarus defence ministry

Our expert correspondents have been talking about the large number of Russian soldiers that are on Ukraine's borders.

But where are they?

Here are some satellite images and a useful map.

Steve Rosenberg
BBC Moscow Correspondent

Image source, AFP via Getty Images

There’s no war, yet, and hopefully conflict can be avoided. The diplomats are still talking.

But, yes, it’s not only Ukraine that’s worried about the possibility of war. Other countries in the region - like the Baltic states of Latvia, Lithuania and Estonia - are concerned that any future conflict could spread to their countries.

Steve Rosenberg
BBC Moscow Correspondent

Basically, Russia’s position is: “Hey, this is our country: we can move our troops wherever we want to on our territory.”

The result: an estimated 100,000 Russian soldiers near Russia’s border with Ukraine. Plus, more Russian troops arriving in Belarus for snap war games. A potential invasion force, says the West. Moscow denies it.

Image source, Reuters