Wikki says its a treaty but I dont know
Then in a way it is more dangerous even if it isn't ratified. The Vienna Convention on the Law of Treaties holds that a treaty is binding upon signature, not just of the President, but ANY public offal designated as representing the nation in the negotiations. Needless to say, the Senate never ratified the Vienna Convention, but the US has been abiding by it ever since as "customary international law." Hence, it is yet another unconstitutional legislative mechanism by the executive branch.