Headed for a showdown

If Iran's nuclear research is considerably more advanced than Iraq's was, as U.S. and British officials claim, Tehran's refusal Monday to continue to cooperate with a U.N. inquiry means it's close to confrontation time for the Islamic republic. Iran, which Western nations accuse of trying to build nuclear weapons, has been stalling investigators from the International Atomic Energy Agency for years while stepping up uranium enrichment; a secret IAEA report alleges Iran added more than 3,000 centrifuges since May, according to the Reuters international news service. Iran, which sits on one of the world's largest reserves of oil, says it is developing nuclear energy to generate power and claims that the IAEA's requests for information exceed its duty to cooperate with the agency. Britain, which claims Iran is showing "contempt" for the United Nations, says it will push for tougher international sanctions to force it to comply. The United States and Israel have threatened military action if diplomacy fails to resolve the standoff. "On the issue of possible military dimensions to Iran's nuclear program, we have arrived at a gridlock. Without Iran's assistance and cooperation, we cannot move forward," a senior U.N. official told Reuters.