Parliamentarians from NATO countries were told Tuesday that attacks with weapons of mass destruction were possible in Europe and the United States, but that the risk could be minimized by global cooperation.

US former senator Sam Nunn, speaking at a meeting of the North Atlantic Assembly, reported on the results of a scenario-based exercise that postulated the detonation of a 10-kiloton nuclear device in Brussels killing 40,000 people and injuring 300,000.

The exercise, codenamed Black Dawn, was organized in Brussels last year by the Nuclear Threat Initiative, of which Nunn is co-founder, and the Center for Strategic and International Studies.

“Terrorist groups cannot make the (nuclear) bomb, no matter how much expertise they have,” Nunn said. “It is not a piece of cake for them to get the material needed.” Nevertheless, Nunn insisted on the need for greater cooperation and prevention.

He said Operation Black Dawn focused on prevention rather than managing the aftermath of an attack, and its goal was to ask what European governments and institutions could do to stop terrorists acquiring and using nuclear, biological or chemical weapons and materials.

The chairman of the parliamentary assembly, Pierre Lellouche of France, said he asked the NTI to present the exercise at the meeting not to scare people but to urge them to consider all possible prevention measures.

Calling on Europe and the United States to “recommit themselves to jointly confronting common security challenges”, Nunn and Lellouche said, “The Black Dawn terror scenario shows the need for truly urgent attention by leaders of the highest level.

“Only such commitment can reduce the risk of this fiction becoming a reality.”