NATO is still the most remarkable alliance in history. It stuck together through 40 years of Cold War, and it then joined together to fight in Afghanistan. In the 1980s, I would not have thought this was going to be possible.

The Western alliance should have supported the Sunni opposition against the Assad regime from the beginning. As far as Iraq is concerned, if it had stayed stable the way it was in 2008, IS would not have been able to expand in Iraq the way they did. The mistake was that Barack Obama withdrew the armed forces from Iraq too fast.

One of the things that ultimately led me to leave mathematics and go into political science was thinking I could prevent nuclear war.

Poles understand perhaps better than anyone the consequences of making toothless warnings to brutal tyrants and terrorist regimes.

We did not go to war in Afghanistan or in Iraq to, quote, 'impose democracy.' We went to war in both places because we saw those regimes as a threat to the United States.

Putin is behaving in a very dangerous way. And Donald Trump sounds as though he would simply sit back and allow that to go on. I worry about where that would end up.

For one thing I tend not to see myself in various moulds that people fit me into.