With Afghanistan now under Taliban rule and the terror threat the worst it has been in years, it is time to reassess the nuclear terror threat. The 20^th anniversary of 9/11 approaches, and as we remember the most world-shifting terror attack to date, we must consider – and work to prevent – the harrowing possibility of nuclear terrorism, writes Philipp C. Bleek.

The September 11, 2001 terrorist attacks on New York and Washington, DC galvanized fears of even worse attacks with nuclear weapons. The 9/11 attacks made clear that some terrorists were motivated to kill large numbers, contrary to the conventional wisdom that terrorists want more people watching than dead. Sophisticated planning and patient execution over many years supported the attacks, including from Al Qaeda’s safe haven in Afghanistan. And Bin Laden explicitly said his organization sought nuclear weapons, and undertook at least some efforts to obtain them. Twenty years later, and as Afghanistan returns to the control of Al Qaeda’s Afghan patrons the Taliban, how should we think about nuclear terrorism risks?