Obama begins airing ad on nuclear weapons

Presumptive Democratic presidential nominee U.S. Sen. Barack Obama (D-Ill.) has begun airing a new ad in the Granite State.

The ad is entitled "American Leadership" and focuses on Obama's work with U.S. Senator Richard Lugar (R-IN) to stop the spread of nuclear weapons.

"The single most important national security threat that we face is nuclear weapons falling into the hands of terrorists," Obama says in the advertisement. "What I did was reach out to Senator Dick Lugar, a Republican, to help lock down loose nuclear weapons."