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Nuclear security refers to the prevention of malicious acts involving nuclear or other radioactive materials and their associated facilities. It is typically used in the context of preventing terrorist groups from perpetrating hostile acts. This POSTnote provides an overview of the key threats to nuclear security, and the UK and international initiatives that seek to address them.

The key points in this POSTnote are:

  • Nuclear security initiatives focus on preventing terrorist groups from carrying out nuclear or radiological attacks.
  • The US and Russia own 93% of nuclear warheads and 82% of nuclear material.
  • There are 24 countries that have 1 kg or more of weapons-usable nuclear material and over 100 that store radioactive sources.
  • Security standards vary widely. Growing cyber threats present a challenge.
  • The Nuclear Security Summit process (2010-16) made substantial progress, but gaps remain. The importance of continued focus on this issue is widely recognised.
  • Military nuclear materials, which account for 83% of total stockpiles, are not covered by international agreements.


POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank the following interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing:

  • Department of Energy and Climate Change (now Department for Business, Energy & Industrial Strategy)
  • Foreign and Commonwealth Office
  • Office for Nuclear Regulation
  • House of Commons Library
  • Royal United Services Institute
  • Dr David Blagden, Strategy and Security Institute, University of Exeter
  • Nuclear Threat Initiative
  • Sellafield Ltd
  • Prof Matthew Bunn, Belfer Center, Harvard University
  • Jacobs Engineering Group & Defence Industry Security Association
  • International Institute of Strategic Studies
  • Dr Andrew Futter, Department of Politics and International Relations, University of Leicester
  • Oxford Research Group
  • Greenpeace

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