During the Cold War, we relied on the doctrine of "mutually assured destruction." We believed that neither the United States nor the Soviet Union would launch an attack because it would produce massive and destructive retaliation. But the world has changed, and we are in a high-risk era when the presence of nuclear weapons raises the stakes for global conflict, accidents and terrorism.

What if someone infiltrated our nuclear command and control so that if we pushed the button, nothing happened? Or if something did happen even without our pushing the button? What if Pakistan did this to India, or India to Pakistan?

Twenty years ago next week, on 8 July 1996, the International Court of Justice (ICJ) issued an advisory opinion regarding nuclear weapons. In a decision that split its fourteen-member bench, the court found, with the president's casting vote:

Of all the accomplishments and disappointments of the Obama presidency, his nuclear weapons policy is the greatest. Yes, you read that correctly. Obama's approach to nukes will be his most significant legacy as well as his most salient failure.