Putin imagined it would be different. So, like many Russian leaders before him, he imagined that Ukraine was basically Russia, but they speak with a funny accent. Actually, it's not Russia; it has a different identity. It has a very different language. Russians don't automatically understand Ukrainian. And, in particular, the way Ukraine has developed over the last two decades is different from the way Russia has developed.

Putin saw the Ukrainian revolution as a challenge to him personally, and I think that's why he, in fact, over-reacted. I think his occupation of Crimea and then annexation for him was actually a mistake from Russia's point of view. And then his invasion of Eastern Ukraine was also a mistake. He imagined that he would invade Eastern Ukraine and then eventually split the country in half, and he discovered that in fact, Russian-speaking Ukrainians are not Russians, and they didn't support him.

The world has always been a dangerous place. Now it is dangerous in a different way, because the world order that we've known since the end of the Cold War has been radically transformed. All of the institutions that preserved peace and promoted global trade will be weaker - NATO, the EU, NAFTA - and US relationships with other countries will change, too.

Americans have long felt that NATO isn't doing its job and that the Europeans aren't contributing enough. Trump has accelerated the decline in Atlantic solidarity by offering open contempt for NATO allies as well. The future of NATO now very much depends on Europeans. Can you begin to identify security threats, prepare yourselves and arm yourselves without the US?

I don't want to predict calamity. But I am afraid of a new Russian occupation of parts of Eastern Europe. Also of a new Russian campaign to exert influence in Germany or other parts Europe, aimed at making continental politics less democratic. I am afraid of a US trade war and even a shooting war with China.

European security may now depend on Germany, France, Britain and one or two others, and it's better to start planning now for the possibility of European-only cyber-defense, counter-terrorism, and conventional defense too.

Khodorkovsky is richest man. And he lost everything when Putin arrested him and took his company away, and essentially took his company away, sold it, and gave it to other people, and enriched them. So, he's a complicated figure as an opposition leader, and people admire him - he was in prison, and he was very brave, and he's written some good things since then, and so on. But at the end of the day, people see him as being part of the corrupt system that has done so much to undermine the Russian system since the 1990s, and I don't know that he can ever be a really popular leader.