I believe the answer you are looking for is Japan - they had a secret nuclear weapons project which was exposed.
As of 2004 their are 8 countries believed to have nuclear weapons:US - about 9000Russia - about 9000China - about 400France - about 350UK - about 200Israel - about 200India - about 60Pakistan - about 35Israel does not publicly admit to having them.
Pakistan has about 100 nuclear weapons.
china
Many countries have nuclear weapons today including the United States. China, North Korea, South Korea, and Japan also have nuclear weapons.
Some of the countries have nuclear weapons because they use them as a defense mechanism. The nuclear weapons are intended to be used whenever there is a war.
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Nuclear weapons are governed by international agreements such as the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which aims to prevent the spread of nuclear weapons. Additionally, there are regional and bilateral agreements that regulate the use and possession of nuclear weapons among specific countries. Some countries also have domestic laws pertaining to nuclear weapons possession and testing.
America has the most nuclear weapons
the first five countries that were involved in nuclear weapons are as follows;United StatesGermanyGreat BritainRussiaArgentina
As the category for this question is "Nuclear weapons", I'm presuming it refers to nuclear arms.As of 2012, the three countries with the largest stockpiles of nuclear weapons are, in order from most to least:RussiaUnited StatesFrance
None. No nuclear weapons were used in Viet Nam.
Proliferation of nuclear weapons refers to the spread of nuclear weapons amongst different countries. First the U.S. had a nuclear bomb; then the Soviet Union had a nuclear bomb, followed by other countries such as the United Kingdom, France, China, India, and so on.