That Iran is building a secret underground facility near the holy city of Qom, under custody of the Revolutionary Guard -- too small to be a production center for nuclear fuel, but just right for the enrichment of uranium to weapons grade -- is grounds for concern, but not panic.

Heretofore, all of Iran's nuclear facilities, even the enrichment plant at Natanz -- kept secret before exiles blew the whistle in 2002 -- have been consistent with a peaceful nuclear program.

Iran has also been on solid ground in claiming that, as signatory to the Non-Proliferation Treaty, she has a right to enrich uranium and operate nuclear plants, as long as she complies with treaty obligations.

Under the Safeguard Agreement to the NPT, these include notification, six months before a nuclear facility goes operational.

According to U.S. officials, construction of this site began in 2006 and is only months from completion. And Tehran did not report it to the International Atomic Energy Agency until a week ago, when they were tipped the Americans were onto it and about to go public.

Iran's explanation: This facility is benign, a backup to Natanz, to enable Iran to continue enriching uranium to fuel grade, should America or Israel bomb Natanz. It is a hedge against attack. And contrary to what Barack Obama implies, the facility is designed to enrich uranium only to the 5 percent needed for nuclear fuel, not the 90 percent needed for nuclear weapons.

Still, the burden of proof is now upon Tehran.

President Ahmadinejad and Ayatollah Khamenei must convince IAEA inspectors this small secret facility that can house only 3,000 centrifuges has the same purpose as Natanz, which can house 58,000. Or they will be exposed as liars -- to the West, to the Russians who have served as their defense counsel and to their own people.

For while Iranians are near unanimous in backing their national right to peaceful nuclear power, they do not all want nuclear weapons. And the Ayatollah has declared, ex cathedra, that Iran is not seeking them, and possession or use of such weapons is immoral and contrary to the teachings of Islam.

If Obama is right that the secret facility is "inconsistent with a peaceful program," but compatible with a weapons program, Ayatollah Khamenei has a credibility problem the size of Andrei Gromyko's, when he assured President Kennedy there were no Soviet missiles in Cuba. And President Kennedy had the photos in his desk.

Diplomats have been called honest men sent abroad to lie for their country. But ayatollahs, as holy men, are not supposed to be descending to diplomatic duplicity.

Obama's dramatic announcement represents a coup for U.S. intelligence, but it also raises questions.

Reportedly, we have known of this Qom facility "for several years." Yet, in late 2007, the National Intelligence Estimate (NIE) said that U.S. agencies had "moderate confidence" that Iran had ended any nuclear weapons program in 2003. Continued...