Anxieties are mounting as nuclear weapons make their way into unstable regions. In a SPIEGEL ONLINE interview, U.S. disarmament expert Richard Burt discusses the growing risk of their use, why allowing Iran to get the bomb could trigger a Sunni-Shiite arms race and how an attack could make citizens demand a police state.

A Russian intercontinental ballistic missile is driven through
Moscow's Red Square in 2009. Photo: AFP.

SPIEGEL ONLINE: Ambassador Burt, you served as the chief American negotiator in hammering out the first Strategic Arms Reduction Treaty (START) in 1991 between the United States and the Soviet Union, which marked a milestone in nuclear disarmament. Is the world safer today than it was 20 years ago?

Burt: In the Cold War, there was the risk of a massive nuclear conflict between the superpowers and their allies. Now you don't have the risk of a huge conflict, but you have a much greater likelihood that nuclear weapons could actually be used on a smaller scale. The damage may not be as great, but we're still talking about the potential of killing many millions of people.

SPIEGEL ONLINE: In 2007, when current Finance Minister Wolfgang Schäuble was Germany's interior minister, he said that it was only a matter of time before terrorist launched an attack using nuclear weapons -- and that one shouldn't waste the remaining time just thinking we're doomed.

Burt (chuckles): That may be an exaggeration. I do think the risk that nuclear weapons will be used is growing. And there's not simply the very real terrorist threat. As proliferation proceeds, deterrents could break down. Between the United States and the Soviet Union, there was an ideological and a strategic competition, but ethnicity, historical rivalries and the kind of hatred that can build up between neighbors did not exist. But if you look at India and Pakistan, you could actually see how a small-scale conflict could actually escalate to the use of nuclear weapons. That's why the spread of nuclear weapons into unstable regions is so dangerous.

SPIEGEL ONLINE: Isn't Iran another good example?

Burt: The problem with Iran is not that there is necessarily going to be an Israeli-Iranian nuclear conflict. In fact, I think the Israelis would probably deter the Iranians from using nuclear weapons. But the danger is that once Iran acquires these weapons, there's the potential for a cascade of other countries to do the same. Turkey, for example, would be very likely to acquire its own nuclear weapons if Iran went that way; Egypt and Saudi Arabia, too. What we could see is a dangerous Sunni-Shite nuclear arms race -- and that is very worrisome.

SPIEGEL ONLINE: Israel's government has made it clear that it will prevent Iran from obtaining nuclear weapons -- and, if necessary, through military means. If their efforts should fail, how big do you think the risk is that a misunderstanding in a crisis situation could trigger a nuclear war?