No nuclear terrorism.

Despite Obama's remarks in 2016 and these two incidents, experts and officials contest the viability of the nuclear terrorism threat. Dr Beyza Unal, a research fellow in nuclear policy at think tank Chatham House, argued there is currently no evidence that terrorist groups could build a nuclear weapon. Similarly, a report by the Council on Foreign Relations in 2006 emphasized how building a nuclear bomb is a difficult task for states, let alone terrorists. This is because of the issues involved in accessing uranium and creating and maintaining it at the correct grade (enriched uranium). While nuclear terrorism is a concern, the majority of terrorist attacks are conducted with conventional explosives. The 2017 Europol Terrorism Situation and Trend Report states that 40 percent of terrorist attacks used explosives. These explosives originate from a wide variety of countries across the world. According to a study by Conflict Armament Research, large quantities of explosive precursor chemicals used to make bombs as seen in the 7/7 attack in London in 2005 and the 2017 Manchester Arena attack, have been linked to supply chains in the United States, Europe, and Asia via Turkey. The threat from the spread of chemical precursors prompted the EU to begin looking at ways to tighten the regulations of these chemicals (PDF). A nuclear terrorist attack would have grave consequences, but it is currently not a realistic or viable threat given that it would require a level of sophistication from terrorists that has not yet been witnessed. The recent focus of terrorist groups has been on simplistic strikes, such as knife and vehicular attacks. If countries are concerned about nuclear terrorism, the best way to mitigate this risk could be to tighten security at civilian and government nuclear sites. But governments would be better off focusing their efforts on combatting the spread and use of conventional weapons.