In his first speech to the U.N. Security Council, U.S. President Barack Obama challenged members to think about the impact of a single nuclear bomb. He said: "Just one nuclear weapon exploded in a city -- be it New York or Moscow, Tokyo or Beijing, London or Paris -- could kill hundreds of thousands of people." The consequences, he noted, would "destabilize our security, our economies, and our very way of life."
Before the Sept. 11, 2001, assault on the World Trade Center and Pentagon, who could have imagined that terrorists would mount an attack on the American homeland that would kill more citizens than Japan did at Pearl Harbor? As then-Secretary of State Condoleezza Rice testified to the 9/11 Commission: "No one could have imagined them taking a plane, slamming it into the Pentagon ... into the World Trade Center, using planes as missiles." For most Americans, the idea of international terrorists conducting a successful attack on their homeland, killing thousands of citizens, was not just unlikely. It was inconceivable.
As is now evident, assertions about what is "imaginable" or "conceivable," however, are propositions about our minds, not about what is objectively possible.
Prior to 9/11, how unlikely was a megaterrorist attack on the American homeland? In the previous decade, al Qaeda attacks on the World Trade Center in 1993, U.S. embassies in Kenya and Tanzania in 1998, and the USS Cole in 2000 had together killed almost 250 and injured nearly 6,000. Moreover, the organization was actively training thousands of recruits in camps in Afghanistan for future terrorist operations.
Thinking about risks we face today, we should reflect on the major conclusion of the bipartisan 9/11 Commission established to investigate that catastrophe. The U.S. national security establishment's principal failure prior to Sept. 11, 2001, was, the commission found, a "failure of imagination." Summarized in a single sentence, the question now is: Are we at risk of an equivalent failure to imagine a nuclear 9/11? After the recent attempted terrorist attack on Northwest Airlines Flight 253, this question is more urgent than ever.
The thought that terrorists could successfully explode a nuclear bomb in an American city killing hundreds of thousands of people seems incomprehensible. This essential incredulity is rooted in three deeply ingrained presumptions. First, no one could seriously intend to kill hundreds of thousands of people in a single attack. Second, only states are capable of mass destruction; nonstate actors would be unable to build or use nuclear weapons. Third, terrorists would not be able to deliver a nuclear bomb to an American city. In a nutshell, these presumptions lead to the conclusion: inconceivable.