At the UN this week, President Obama will finally move closer to closing the notorious "enrichment loophole"—a monstrous oversight written into the 1968 Nuclear Non-Proliferation Treaty (NPT) that allowed North Korea and Iran to pursue nuclear-arms programs while insisting that their efforts were simply peaceful civilian research. Because the treaty grants every state that forswears nuclear arms a "right" to peaceful nuclear technology, rogue regimes can claim that they are exercising their sacrosanct "right" while they are, in fact, doing the one thing that should cause their privilege to be revoked.

Now, Obama is quietly taking steps to close the loophole. His draft UN resolution includes language that implies states would waive their access to nuclear enrichment if they have not complied with all of the monitoring and safeguard provisions stipulated by the IAEA. It also says that states should have to give up the fruits of their "peaceful" nuclear progress if they subsequently withdraw from the NPT. If Obama can change the scope of the treaty's guarantee, that would be fantastic: Mahmoud Ahmadinejad would be less able to argue that Iran is a global citizen in good standing, while it continues to enrich uranium and play rope-a-dope with UN inspectors.

But there's also a glaring complication. Major changes to the NPT will inevitably raise questions about the less-regulated nuclear programs of U.S. allies Israel, India, and Pakistan. Indeed, the IAEA has just taken the unprecedented step of requesting that Israel submit its nuclear program to international safeguards and join the NPT. In the midst of his effort to strengthen the NPT and isolate Iran, Obama has slackened America's usual efforts to protect Israel's nuclear program from international scrutiny.

All of which means that Obama's new nuclear push is likely to be very complicated, uncomfortable, and not a little bit ugly. And ultimately, even if he does manage to revise the terms of the NPT's "nuclear bargain," there will still be several states whose nuclear programs exist in safeguards limbo outside of the NPT. Until he manages to shepherd those countries into other agreements that cap their arsenals and limit the potential for proliferation—such as the Comprehensive Test Ban Treaty (CTBT), or the Fissile Material Cutoff Treaty (FMCT)—there will still be plenty of avenues for more atomic mischief.

Related: Obama shifts nuclear policy before the UN meeting -- "These Are The President's Weapons"