“We are more than a decade removed from the September 11 attacks. But when I spoke to Allison [Graham T Allison, professor of political science at Harvard, former advisor to Reagan & Clinton] in 2010 he reaffirmed the gravity of threat he perceives. It’s one that he takes quite literally, in fact. I called Allison from my desk at the New York Times office, a block from Times Square. Allison told me that he’d be at least a little bit nervous in Times Square and wasn’t sure if he’d be willing to work there every day.
Allison’s probability estimate doesn’t come from a statistical model. Instead it’s ‘the basis on which [he]’d make bets.” Why does he see so much risk? ‘It’s a knockoff of the old Sherlock Holmes version of motive, means and opportunity,’ he told me.
The motive of terrorists, for Allison, is easy to discern. Osama bin Laden has said that he wanted to kill four million Americans, a number that could probably be achieved only through a nuclear attack. The modus operandi of Al Qaeda has been what Allison calls ‘spectaculars’ – occasional but astonishing attacks that kill large numbers of innocent people. And the CIA had picked up Al Qaeda chatter about an ‘American Hiroshima’ before the September 11 attacks.
By opportunity, Allison means the ability of terrorist groups to smuggle a weapon into the United States. He has little doubt this could happen. ‘How do crooks get into American cities every day?’ Allison asked me. The United States has more than 3,700 ports, and receives more than six million cargo containers per year – but only 2 percent of them are physically inspected by customs agents. ‘If you have any doubt, they could always hide it in a bale of marijuana,’ Allison half-joked.
So Allison is mostly focussed on the means – the ability of a terrorist group to acquire a nuclear weapon. If we want to reduce the risk of a nuclear version of 9/11, controlling the means would be the way.
Experts believe there are about 20,000 nuclear warheads in the world today – down from a peak of 65,000 in the 1980s. A threat could theoretically come from any of the nine countries that possess nuclear weapons today – even the United States has lost track of eleven of its nuclear weapons throughout its history – and other countries may be trying to develop them. But Allison’s concern stems primarily from two nuclear states: Russia and Pakistan.
In Allison’s view, the risk has lessened some in the former country. In part because of successful programs like the one sponsored by senators Sam Nunn and Richard Lugar, there are no longer active nuclear weapons in the outlying states of the former Soviet Union. And in Russia itself, the number of nuclear weapons has declined to 11,000 today from a peak of 30,000 in 1985.
If the risk in Russia has been reduced, however, the threat posed by Pakistan has increased – perhaps markedly. ‘If you map weapons of mass distruction and terrorism, all the roads intersect in Pakistan,’ Allison told me.”
Nate Silver, The Signal and the Noise (2012)