"This action is part of our comprehensive sanctions effort to apply pressure on the Iranian government to meet its international obligations with regard to its nuclear program," US National Security Council spokesman Tommy Vietor said in a statement accompanying the sanctions announcement.
"This sanctions effort has produced profound and demonstrable results."
But Mark Dubowitz, executive director of the Foundation for Defense of Democracies and a proponent of increased sanctions, said that while the sanctions have had a tremendous effect on the Iranian economy, "there's no evidence to date that sanctions have changed the calculus of Iran's leaders with respect to their pursuit of nuclear weapons."
Dubowitz described Tuesday's action as mostly technical in nature. Still, he said, the signing of the executive order made a significant statement.
"For the psychology of it, repetition is the key to success of message penetration," he said.
"If you're going to send a message to the Iranian regime that the administration is serious about economically crippling them, then I think this executive order plays an important role."
He added that there was also a political message, as Obama wanted to seem "to be aggressive about the implementation of sanctions and is not just being dragged kicking and screaming by Congress," as Republicans have made out.