By Joe Sterling, Jessica Yellin and Holly Yan

Sen. John Kerry, the president's nominee for secretary of state, put America's anxiety over Iran front and center during his confirmation hearing, saying the "questions surrounding Iran's nuclear program" must be resolved.

"The president has made it definitive," Kerry told the Senate Foreign Relations Committee Thursday during what is expected to be an easy confirmation process.

"We will do what we must do to prevent Iran from obtaining a nuclear weapon, and I repeat here today, our policy is not containment. It is prevention, and the clock is ticking on our efforts to secure responsible compliance."