The adjective "sole" has become a key measurement in diplomatic circles where U.S. nuclear forces have long been seen as an impediment to stopping nuclear proliferation.

WSJ: U.S. Keeps First-Strike Nuclear Strategy

The public's top foreign-policy goals (see chart) are preventing the spread of nuclear weapons, stopping the flow of illegal drugs into the country and protecting the jobs of American workers.

ECONOMIST: View from the summit

And you will continue to do that by stopping the nuclear threat that affects us all throughout the world.

WHITEHOUSE: President Obama Meets with Peruvian President Garcia

Even if deadlocked nuclear disarmament negotiations resume, analysts see no easy solution to stopping North Korea's nuclear weapons drive.

NPR: NKorea: Cold War History With US Justifies Nukes

We also share a common interest in stopping the spread of nuclear weapons.

WHITEHOUSE: President Obama Addresses the British Parliament

Kennedy now contended that both sides had a vital interest in stopping the spread of nuclear weapons and slowing the arms race--a contention which led to the test ban treaty of 1963.

WHITEHOUSE: John F. Kennedy

In 2012, Hagel co-wrote an opinion piece with a bipartisan group of former congressmen and military leaders on stopping Iran from getting a nuclear bomb.

CNN: A reality check for Chuck Hagel bashers