出典:Wikipedia
出典:『Wikipedia』 (2010/10/22 13:00 UTC 版)
Nuclear umbrella refers to a guarantee by a nuclear weapons state to defend a non-nuclear allied state. It is usually used for the security alliances of the United States with Japan, South Korea, the North Atlantic Treaty Organization (much of Europe, Turkey, Canada), and Australia, originating with the Cold War with the Soviet Union. For some countries it was an alternative to acquiring nuclear weapons themselves; other alternatives include regional Nuclear-Weapon-Free Zones.