WASHINGTON: A dramatic visit by UN inspectors to Iran amid rising international tension failed to get answers about whether Iran seeks the bomb.

This raises concerns the Islamic Republic may be trying to delay tough economic sanctions against it rather than responding to the growing international suspicion about its nuclear ambitions.

Iran tried to draw maximum publicity through a show of cooperation with inspectors from the UN watchdog International Atomic Energy Agency who visited Tehran this week. Iranian Foreign Minister Ali Akbar Salehi said Iran was "prepared to make arrangements for inspection" of nuclear sites but that the IAEA team had not asked to go.

But IAEA chief inspector Herman Nackaerts and the agency number two Rafael Grossi, who headed the inspectors, did not want to visit nuclear sites, which are already monitored by the IAEA. They wanted to see Parchin, a weapons testing ground, and also to see crucial documents and scientists who work there or are connected to such work, diplomats said. The IAEA had published in November an extensive report about alleged atomic weapons research by Iran, and Parchin was a key link in this. The IAEA has also been seeking for years to interview the man believed to head Iran's alleged covert military nuclear program, Mohsen Fakhrizadeh, and once again did not get to him.

The Iranians refused access to Parchin, saying it was not a site where there is nuclear material and so the IAEA which verifies use of such material had no business there. This, however, goes to the crux of what the IAEA is now trying to do, which is to verify possible nuclear weapons research that may have been carried out without nuclear material. This can include learning how to make the trigger which sets of atomic bombs or the neutron initiator which speeds up the explosive chain reaction. The IAEA needs to investigate such matters, grouped under the heading "possible military dimensions" of Iran's nuclear work, before it can say whether the Iranian program is a peaceful or military one.

Agency inspectors had visited Parchin twice in 2005 and found nothing unusual. The IAEA now has new information about a containment vessel built at the site for explosions tests, and it is probably this site they want to see. One diplomat stressed, however, that the IAEA's interest in Parchin extends beyond any one locale but has to do with the nature of work done there and how it was organized.

Iran's willingness to open its doors to a senior IAEA team was seen as a hopeful sign in what is an escalating confrontation. The United States and Europe are imposing sanctions on the purchase from Iran of oil, the lifeblood of its economy. Congress may call for even tougher measures. Iran has responded to the punitive measures with threats to cut off the Strait of Hormuz, through which a third of the world's sea-transported oil passes. The United States successfully called Iran's bluff, sending the aircraft carrier USS Abraham Lincoln through the straits late last month. To make sure Iran got the message about the straits international stature, the carrier was escorted by French and British ships as she passed through the narrow passage. Closing the straits to international shipping, could, of course, lead to conflict with the US Navy and to a world economic crisis. To complete the picture, there are growing noises from Israel about a possible military attack against Iran's nuclear installations.

The IAEA inspectors are set to return to Iran on February 21. The agency said in a terse press statement from its headquarters in Vienna that it is "committed to intensifying dialog. It remains essential to make progress on substantive issues." Diplomats said a road map for going forward remains to be finalized even if the Iranians apparently told Nackaerts they were ready to answer questions about possible military dimensions of their nuclear work.

If the Iranians do this, it will be a major breakthrough. The Iranians have refused to clarify these issues and have blocked any meetings about them since August 2008. Their stonewalling this week over Parchin is not a good sign nor is a past during which the Iranians have agreed to talks when threatened with sanctions or other such measures, only to delay answering while they drag out talks as long as possible.

The jury is still out on whether Iran is ready to cooperate, even with international pressure rising sharply against it.

[Eds. note: The photo is of Natanz, Iran where enrichment of nuclear fuel is underway.]