why not just call it "The United Nations"? when you think about it, the Zentradi and Meltrandi were a nation in itself with their own set of principles, industry, and warrior culture upon their unification/integration with humankind right after the first stellar war. they just sort of joined UN as a new intergalactic member.
i say culture because, unbeknownst to the Zentradi, humanity actually does have a warrior culture in portions of the planet a few millenia ago, if not now. waging wars big or small just happens to be every man's favorite pastime since time immemorial.