Iran has been calling for it for years, and the Arab countries support it. Everyone except the United States and Israel support it. The U.S. won't allow it because it means inspecting Israel's nuclear weapons. The U.S. has continued to block it, and in fact blocked it again just a couple of days ago; it just wasn't widely reported. Iran's nuclear program, as U.S. intelligence points out, is deterrent, and the bottom line is that the U.S. and Israel don't want Iran to have a deterrent.