The limitations on nuclear weapons are not clear and consistent. A country which is a signatory to the Nuclear Non Proliferation Treaty (around 140 countries) agrees to not increase its capability and to not supply materials or information to countries who do not yet have them. North Korea signed but then withdrew. Israel never signed.
This status quo and unless a country has made a commitment not to acquire nukes (like Iraq agreed in its surrender after the Gulf War) there is no real limitation.
Acknowledged Nuclear Weapons Capability Britain China France India Pakistan Russia United States
Unacknowledged Nuclear Weapons Capability Israel
Seeking Nuclear Weapons Capability Iran Iraq North Korea
Abandoned Nuclear Weapons Development South Africa—Constructed but then voluntarily dismantled 6 uranium bombs. Belarus, Kazakhstan, Ukraine—When Soviet Union broke up, these former states possessed nuclear warheads that they have since given up.
In Dec. 2002, North Korea revealed that it had violated its 1994 agreement to freeze its nuclear weapons program and has been developing a nuclear bomb. Source: U.S. State Department and Time magazine.
Certainly the big nuclear powers can keep their nukes.
