Ukraine crisis: 'I don't want to fight in a war'
Russia says it has the right to protect its interests and those of Russian speakers in Ukraine by armed force, if necessary.
In response Ukraine has mobilised troops and called up military reservists in what is becoming a rapidly escalating crisis described by the interim Prime Minister Arseniy Yatsenyuk as "the brink of disaster."
It comes after parliament dismissed President Viktor Yanukovych following weeks of protests in Kiev that spread to other parts of Ukraine.
Here a Maidan protester tells BBC News whether he thinks it was worth it.
Sergii Bielov, 36, from Kiev, took part in the Maidan protests
"I am Ukrainian and both of my parents are Ukrainian too. This is our country.
Crimea is part of Ukraine too and it is not right that Russia should take it or send troops here.
But am I prepared to fight for it? I don't know.
I feel like this is not a war worth dying for. It is a war of politics. This is not about the people.
When we were protesting in the Maidan, we knew what we were fighting for. It was about corruption and removing the president. There were criminals in government and in one year Ukraine was going to default.
But nothing is worth people's lives.
It's really hard for me to go back to the square where people were killed.
It's not just the people who died either. There were many people injured too. My wife and I have been visiting them in the clinics.
They will struggle for the rest of their lives. I asked them 'If you could return to the moment before you were hurt, would you do the same again?' and most of them said there was a high chance they would.
Would I? I don't know.
We did not know then that removing Yanukovych could lead to war. I don't want to fight in a war. I would be scared of dying.
But if Russian troops started fighting Ukrainian troops and you put a rifle in my hand, then yes I would probably fight, but I wouldn't want to.
No-one wants war.
I have Russian friends and relatives in Syktivkar in Russia. I can't imagine having to shoot them or them shooting me.
I work in IT programming and before this year I had never taken part in any protests or strikes. The police action was a trigger that opened my eyes to the corruption.
In the beginning the protest was about integration with the EU, but I did not feel very strongly about it.
Then I saw how the police treated people protesting in the square. After that moment it wasn't about integration, for me it was about the behaviour of our government.
In the week I went to work as normal and I obeyed the law. At the weekend I went down to the Maidan and joined the protests for about nine days in total.
I didn't have a placard or any weapons, I just stood there with the others. It was enough for me just to be there and to feel like I was having my say.
To my shame I wasn't there at the critical moment at the end of February. I was too scared.
I had no idea how it was going to end. I suppose I thought the protests would continue for a while and then people would grow tired and would eventually go home. I did not believe anything would change, but I felt that I had to do something, even though I didn't know exactly what.
When I heard that Yanukovych had left Kiev, I didn't feel anything for him. I didn't care about him or his country house, I was only thinking about the people who had died. He is an ex-politician and not worth the blood of anyone.
I was standing in the place where those people died and I was crying.
After some time had passed I was glad that he had left.
I don't believe in the new government either. They are from the same groups, they have the same politics, they move from one cabinet to another. The only difference is the flag colour has changed. But they are still the elites.
'Chance to avoid war'
It was a big shock for them to see what people can do, to rise up against a president. I hope they will remember this in future.
I hope too the rest of the world makes Putin remove his troops. I don't want the World to provide their own troops though, that would cause World War Three.
I just hope they can talk him down.
For now, although there are many Russian troops, no-one is shooting in Crimea. Yes, they are provoking, but no-one is dying.
There is still a chance we can avoid war. If we do not, we will be the second Georgia or Chechnya and many people will lose their lives. That could be me.
Interview by Sitala Peek