Nuclear security is the whole range of measures intended for the prevention and detection of, and response to, theft, sabotage, unauthorised access, illegal transfer or other malicious acts involving nuclear material, other radioactive substances or their associated facilities.

The definition of nuclear non-proliferation, if we stick what is given in the dictionary, seems a little simplistic. It basically defines this as “limiting the amount of nuclear weapons around the globe”. Other dictionaries elaborate on this by defining non-proliferation as: “a policy to prohibit the acquisition of nuclear weapons by countries which do not possess them”.

For the sake of completeness, these definitions could be clarified by stating that international non-proliferation regimes are all the international instruments and policies that contribute to the prevention of access by states to weapons of mass destruction (nuclear, chemical, biological) and their delivery systems (missiles), in violation of their international commitments. These international regimes may be accompanied by commitments and measures for disarmament.

"Nuclear" materials are materials that could be used to manufacture a nuclear explosive device, which are subject to specific regulations in the fight against nuclear proliferation. Three materials are covered by the international regulations: plutonium, uranium and thorium.