Nuclear Proliferation in Iran, and the International Threats Posed. Introduction Nuclear proliferation is a term used to describe the spread of nuclear weapons and weapons- applicable nuclear technology and information to nations which are not recognized as Nuclear Weapon States by the Treaty on the Nonproliferation of Nuclear Weapons Treaty (NPT). Proliferation has been opposed by many countries. This opposition comes even from nations that are without nuclear weapons too. Most nations feel that if more countries are allowed to have nuclear weapons and nuclear technology, then nuclear warfare is a possibility, and many civilians will be the target of such warfare. In addition, it would destabilize international or regional relations or even worse infringe on the sovereignty of states. During World War II, research into the development of nuclear was undertaken by the United Kingdom, Germany, USSR, Japan and the United States