An attack on a key Iranian nuclear facility might not be effective, even if the U.S. military's massive bunker-buster bombs are used, a national security expert familiar with Iran's program said. While the 30,000-pound bombs have been tested, they've never actually been used and the exact nature of the concrete and metal protecting the site located deep inside a mountain -- that the bombs would need to penetrate -- isn't fully known. Joe Cirincione, who has spent decades researching nuclear