Defense Secretary Robert Gates says that he thinks economic penalties rather than diplomacy are more likely to bring success to US efforts on Iran. Gates says that if enough economic pressure is placed on Iran, diplomacy might provide what he calls "an open door" for Iranians if they choose to change their policies. Gates says economic penalties are likely to get the Iranians to the table. The defense secretary says Iran is not close to obtaining a nuclear weapon. He says Tehran lacks the capability at this point to enrich enough uranium to the levels needed for a weapon. Gates appeared on "Fox News Sunday."