Successive U.S. presidents have insisted that a nuclear-armed Iran is "unacceptable." Iran's Islamic leadership insists that its nuclear program is for peaceful purposes only, but even as U.N. inspectors headed to Tehran in late January, the body of evidence from earlier inspections raised nagging questions that the Iranians have failed to answer, such as why facilities for a peaceful program would be buried hundreds of feet underground. A nuclear Iran would alter the strategic balance in the tense Middle East and, some say, possibly trigger a regional atomic arms race. Although the United States and Europe have imposed tough economic sanctions on Iran, it has not stopped its uranium-enrichment activities or begun operating its nuclear program with more transparency. But with Israel reportedly considering a pre-emptive strike on nuclear facilities in Iran -- which has vowed to destroy Israel -- the question of the sanctions' effectiveness may be moot.

Roland Flamini is a Washington-based correspondent who writes a foreign-affairs column for CQ Weekly. Fluent in six languages, he served as Time magazine's bureau chief in Rome, Bonn, Beirut, Jerusalem and the European Common Market and later served as international editor at United Press International.