Since when do I love the UN?
No, no, no. The NPT says you CAN'T have nukes if you don't already possess them, and no one can help you develop them. So if you sign it, you are not supposed to develop nuclear weapons, or you are in violation of the treaty. Countries who haven't signed it (Israel, India, Pakistan), or have removed themselves from it (north korea), are a very significant threat, as they have snubbed the international community, and blantantly declared that they will develop nukes.
While this in itself is alarming, a country breaking the NPT (which also sets up regulations for nuclear power development), basically opens itself up to military conflict without much debate. Iran is treading the edge of the NPT, and if they cross it (or have crossed it), there is an extremely good chance the majority of the world will come down on them hard. Even if the countries of the UN themselves don't participate in the military action, they will certain allow us to tear them apart.
While I currently think an invasion of Iran would be unnecessary, I can certainly see air strikes against them being fully validated if they do not co-operate. Honestly, the administration is doing a pretty good job sticking to diplomacy with Iran (maybe they are actually learning something), but patience with this country, which EVERYONE can see as a potential threat, will expire sooner or later, unless they come into line with NPT guidelines.