This layer presents former and current nuclear powers as well as those states where nuclear weapons are stored for the year 2018.
The Non-Proliferation Treaty differentiates between states that produced and fired a nuclear weapon or any other nuclear explosive before its conclusion—they are considered to be nuclear weapon states under the terms of the Treaty. Nuclear powers outside of the Treaty are states that have declared officially that they possess nuclear weapons and that have not signed the Treaty. States whose territory is used to store nuclear weapons owned by another state under the NATO / US umbrella are defined "Stationed nuclear weapons by the USA". Former nuclear powers are states that have given up pursuing their nuclear weapons programme or the former states of the Soviet Union.