New START Treaty

Iran nuclear deal is key to Obama's nonproliferation agenda

In the spring of his first year in office, President Obama began pushing an audacious goal — to use diplomacy to bring about what he called "a world without nuclear weapons."

Before long, his campaign sputtered. North Korea tested nuclear weapons, partly in an effort to provoke the United States. Relations with Russia worsened, rousing memories of the Cold War standoff and complicating a growing global drive to disarm. Nine countries still have nuclear weapons.

Those setbacks make this week's framework deal to limit Iran's nuclear activities crucial to Obama's nonproliferation agenda, administration officials say. If a final deal is reached, they believe it...