The Terrorist Threat From ISIS May Be About to Get Worse

The nuclear threat is real.

The fallout from the ISIS-claimed attacks in Brussels is all bad and certain to get worse. As ISIS loses territory in Syria and Iraq, it lashes out with terrorist strikes abroad, especially against countries supporting the military campaign against it. Its targets are “soft” … and somehow made more vulnerable by the incompetence of Belgium’s authorities, who needed four months to capture the last of the plotters of the Paris attacks. “The most wanted man in Europe,” Salah Abdeslam, was found 100 meters from his childhood home in Molenbeek, the Muslim neighborhood that stands hard by the clean and orderly headquarters of the European Union. The dream of a united Europe, sorely stressed over the past year by the arrival of more than a million migrants and refugees, mostly from the Middle East, has grown brittle to the point of breaking. The Brussels attack will strain it further.

For officials who track terrorism, a whole new level of alarm lurks just beyond the horizon. After the Brussels attack everyone had been expecting–“What we feared has come to pass,” said Belgian Prime Minister Charles Michel–the capital city went into lockdown, which made sense. But so did the country’s nuclear plants.

The extraordinary measure–all but a few employees were told to stay away until further notice–did not come out of the blue. Recent weeks have brought growing evidence that ISIS is actively seeking weapons of mass destruction, including nuclear material. The evidence is piecemeal but alarming to counterterrorism experts who’ve watched ISIS grow increasingly aggressive. And the most dramatic evidence of a possible nuclear plot surfaced, where else, in Belgium–a country with a spotty record both of stopping terrorism and protecting its nuclear facilities.

While investigating the Paris attacks, which had been plotted in Molenbeek, police discovered an unsettling bit of video footage in a suspect’s home. A camera had been hidden in bushes and tilted to capture the front of the residence of a senior researcher at the Belgian Nuclear Research Centre. That facility contains highly enriched uranium, which could be used in a crude nuclear weapon. The site also contains radioisotopes, molecules that carry a specific radioactive energy. They’re intended for medical use, but in potent forms they could be dispersed in a crude explosive known as a dirty bomb.

A senior U.S. official tells TIME that it remains unclear what nuclear materials the ISIS members were hoping to obtain (perhaps as ransom for a kidnapped family member, which would account for the camera recording the household’s comings and goings). But what’s not in doubt is that U.S. officials now consider radiological terrorism–the makings of a dirty bomb–the more immediate danger.

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