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.

The surge in right-wing populism and the phenomenon of Trump are related. You can think of them together as the same problem.

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?

Putin discovered that when he invaded Ukraine, he expected the Ukrainians to rise up and join him and say, "Yes, we want to be part of Russia," and that didn't happen. And they've been paying, actually, I think quite a high price for it, both in the ongoing war in Ukraine - which is I think increasingly unpopular in Russia - and also in the Western sanctions, and in general, the separation from the West that was caused by that.

Donald Trump may undermine some of the traditional checks on the presidency: the press in particular, but also the various government and Congressional ethics bodies, as well as the career civil service.

The Soviet Union was, by the 1970s and 1980s, relatively stable and predictable. Putin's Russia is much more volatile. Nuclear policy is really in the hands of one person, or a small group of people, instead of a huge party-state apparatus. The possibility of a mistake is greater now.

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.