The International Court of Justice (ICJ), which has its seat in The Hague(The Netherlands), the principal judicial organ of the United Nations, on 8 july 1996 unanimously voted for this :

The full document is very long and need to be studied carefully to find the real significance. I have not the competence to do that .
In Belgium we use this as an argument to put legal and political pressure on the government to force the US to  take away their nuclear bombs from Belgian territory. (The US has one such storage base here with estimated 10 bombs)So far we had little succes, but the political consensus about is growing and the arguments of the ICJ have a very important influence.

The struggle of man against tyranny is the struggle of memory against forgetting.(Kundera)