While not a NATO issue, in the "Budapest Memorandum on Security Assurances" Ukraine agreed to give up their nuclear weapons in exchange for a guarantee of UN Se

While not a NATO issue, in the "Budapest Memorandum on Security Assurances" Ukraine agreed to give up their nuclear weapons in exchange for a guarantee of UN Security Council assistance if they were threatened or attacked with nuclear weapons. Russia specifically signed this agreement promising not to threaten or attack Ukraine with nuclear weapons.