The U.S. has shot back at Iran, saying the enrichment of uranium has escalated the nation's violations of U.N. resolutions. Earlier, diplomats confirmed Iran's claim that it's begun the enrichment at a secure underground bunker. Iran's state media claimed that enrichment has begun at the country's Fordo site near the holy city of Qum. The Fordo centrifuges are reportedly producing uranium enriched to 20 percent, far higher than the 3.5 percent made at Iran's primary plant. The new uranium can more easily be made into warhead material, and the bunker—underground and protected by air defenses—is difficult to attack. If Iran is using the uranium for a weapon, American officials estimate they would have six months to a year to react before Iran finished enriching weapons-grade uranium. Meanwhile, Ahmadinejad met in Venezuela with Hugo Chavez—and the joked about the bomb.