The threat of a terrorist group like the Islamic State (ISIS/ISIL) using nuclear material to carry out a “dirty bomb” attack against the West is the highest since the Cold War came to an end, warns a leading international think tank on proliferation.

According to the International Luxembourg Forum on Preventing Nuclear Catastrophe, the jihadist group is “actively trying to acquire weapons of mass destruction [WMDs]”:

[ISIS] has already carried out numerous chemical weapons attacks in Syria; we know it wants to go further by carrying out a nuclear attack in the heart of Europe. This, combined with poor levels of security at a host of nuclear research centers in the former Soviet Union mean the threat of a possible ‘dirty-bomb’ attack on a Western capital is high.

The Independent reports that Dr. Viatcheslav Moshe Kantor, the think tank’s president, declared:

[ISIS] has already carried out numerous chemical weapons attacks in Syria; we know it wants to go further by carrying out a nuclear attack in the heart of Europe. This, combined with poor levels of security at a host of nuclear research centers in the former Soviet Union mean the threat of a possible “dirty-bomb” attack on a Western capital is high.

The warning from the organization is consistent with a June 2015 assessment by Australia’s Foreign Minister Julie Bishop. Citing Australia’s departments of Defense and Foreign Affairs, as well as NATO, she told The Australian that ISIS had gained access to radioactive material from hospital and research centers in territory it captured in Iraq and Syria, raising the likelihood that the jihadist group could develop a large “dirty” bomb.

Moreover, ISIS, in the ninth edition of its propaganda magazine Dabiq, published last year, indicated that it could purchase a nuclear weapon in Pakistan, take it to Nigeria, and then smuggle it into the United States through Mexico by using existing trafficking networks in Latin America.

ISIS has established a growing presence in the region of Pakistan, the only Muslim nation with a nuclear arsenal.

The most recent warning, issued by the international think-tank, comes amid concerns that ISIS will attempt to carry out attacks during the upcoming Euro 2016 soccer championship in France, reports The Independent.

Although the forum did not explicitly suggest that a terrorist nuclear attack is likely to occur during the tournament, Dr. Kantor noted that the jihadist cell linked to the Brussels attacks earlier this year were believed to be monitoring employees and the security apparatus at a Belgian nuclear facility.

“Their previous documented attempts to gain access to a nuclear power station in Belgium are evidence of their intent,” he told an international conference in Amsterdam. “The terrorists don’t necessarily have to use a ‘dirty bomb.’ We are not just talking about stolen nuclear material; using conventional explosives in a nuclear plant, such as smuggling in a bomb, would have catastrophic consequences.”

“It shouldn’t be a surprise that if terrorists get hold of nuclear material they will try to use it. We also know that they are seeking such material; there were reports, for example, of Isis getting hold of uranium when they captured Mosul,” added former U.K. Defense Secretary Des Browne, a member of the forum and vice-chairman of the Nuclear Threat Initiative (NTI), noting that the threat of nuclear terrorism required attention from the international community.

In 2015, the Australian foreign minister said that the nuclear threat linked to ISIS is severe enough to have gained the attention of the Australia Group, an alliance of about 40 nations, plus the European Community, established 30 years ago to prevent the export of materials that can be used to develop chemical, biological, and radiological weapons.

“It isn’t that hard to build a ‘dirty bomb.’ They may not kill that many people with such a bomb, but the effect on the environment, the infrastructure and the psychological impact on people would be devastating,” explained Browne. “They can also use cyber warfare to target a nuclear facility.”

“We know that terrorist organizations have the desire to get access to these raw materials and to have a nuclear device,” added Ben Rhodes, U.S. President Barack Obama’s deputy national security adviser.