Do you consider yourself to be primarily a scientist or a political activist?

If the world would go away, I would be happy to keep to the science, which is much more interesting and challenging. But the world has an unfortunate habit of not going away and the problems are quite urgent.

What are your thoughts on President Obama?

He's involved in war crimes right now. For example, targeted assassinations are war crimes. That's escalated quite sharply under Obama. If you look at WikiLeaks, there are a lot of examples of attacks on civilians.

What did you think when he was given the Nobel Peace Prize?

Considering the history of the Nobel Peace Prize, it's not the worst example. It was given to him before he had the time to commit many war crimes.

Is there any point in us being in Afghanistan?

We wouldn't have asked in 1985: "Is there any point in the Russians being in Afghanistan?" The fact is that the invasion was a crime. Then comes the question: "Is there any point in continuing?" But that presupposes legitimacy. Putting aside questions of morality and legality and simply asking about the goals of the US government is a very narrow consideration.

What would you like to see happen next in Afghanistan?

There has to be an internal political settlement. Like it or not, the warlords and the Taliban are Afghans, so there has to be a settlement among them. The regional powers also have to be involved, including Pakistan, India and the US - because it's there, not because it belongs there.

Do you worry about Obama's lack of experience in foreign policy?

I don't think that experience is a very useful or convincing attribute for a sensible foreign policy. Henry Kissinger had a lot of experience. [And he still became involved in] the major mass murders in Cambodia.

Is the focus of US foreign policy right?

Let's take the main focus: the Iranian threat. The brutal, clerical regime is a threat to its own population, but it's hardly unique in that respect. The threat to the US came in the presentations to Congress by Pentagon officials in April - they pointed out that the threat is not military; it's to the "stability" of the region.

Do you agree with that assessment?

It's imperial doctrine. Stability is when the UK and US invade a country and impose the regime of their choice. But if Iran tries to interfere, that's destabilising.

What do you make of David Cameron?

It's too early to say much. I haven't been greatly impressed by his policies or his statements.

He recently identified the UK as the junior partner in the "special relationship".

That's too bad for England. It's been a very injurious relationship for England for a long time.

Do countries such as Bolivia have lessons to teach the rest of the world?

Yes. The poorest country in South America, Bolivia had been devastated by neoliberal economic policies. In recent years, the majority of the population won significant battles against privatisation of water. They then entered the political arena and elected someone from their own ranks, and people really engaged with the issues. Their economic growth is now, I think, the best in Latin America.

Are you optimistic about the future of the left?

I don't think it makes much sense to be optimistic, but there's not much point in speculating, either. Either way, the tasks are the same.

Do you vote?

I often do, without much enthusiasm. In the US, there is basically one party - the business party. It has two factions, called Democrats and Republicans, which are somewhat different but carry out variations on the same policies. By and large, I am opposed to those policies. As is most of the population.

What would you like to forget?

There are a lot of things I regret - for example, the Indochina war. I was deeply involved with it, facing a long jail sentence. But I deeply regret that I didn't get involved until the mid-1960s, which was much too late.

Was there a plan?

Well, I had some general guidelines. They're so banal I hate to say them. But what's not banal is applying them in particular situations.

Are we all doomed?

If there was an observer on Mars, they would probably be amazed that we have survived this long. There are two problems for our species' survival - nuclear war and environmental catastrophe - and we're hurtling towards them. Knowingly. This hypothetical Martian would probably conclude that human beings were an evolutionary error.