VIENNA The U.N. nuclear watchdog's increased access in Iran to monitor a landmark agreement with world powers still falls short of what it says it needs to investigate suspicions that Tehran may have worked on designing an atomic bomb.
It is also a far cry from the wide-ranging inspection powers the International Atomic Energy Agency had in Iraq in the 1990s to help unearth and dismantle Saddam Hussein's clandestine nuclear program after the first Gulf war.
Nevertheless, the IAEA will see its role in Iran expand significantly under the November 24 interim accord between the country and the six major powers, the implementation of which will start next Monday.
Since the deal is only preliminary, the IAEA and its investigation may gain more prominence in later talks on a final settlement of the decade-old dispute over Iran's nuclear program, but it remains to be seen how far it will go.
"This is just an appetizer, I guess ... a starter," former chief U.N. nuclear inspector Herman Nackaerts said.
The deal struck in Geneva seven weeks ago focuses on capping Iran's output of fissile material, which can be used for atomic arms if refined further, and not on any research it may have undertaken in how to make a bomb out of it.
Western diplomats and nuclear experts say the IAEA also needs to carry out its long-stalled inquiry into alleged tests and other activity by Iran that could be used for nuclear arms development, partly to make sure that any such work has ceased.
The IAEA is pursuing separate talks with Iran in an attempt to restart its probe, but progress may depend on the broader diplomacy between Tehran and the powers.
Nackaerts, who retired as IAEA deputy director general last year, said the Geneva agreement was a good first step.
But, he told Reuters, "more has to come to be able to resolve all the outstanding issues, that is quite clear."
To check that Iran meets its side of the six-month accord to curb sensitive nuclear activity in return for some sanctions easing, IAEA experts will go daily to Iran's uranium enrichment sites at Natanz and Fordow, up from about once a week now.
They will also inspect plants where Iran is manufacturing the specialized equipment, centrifuges, used to enrich uranium, as well as uranium mines and mills.
However, the agreement between Iran and the United States, France, Germany, Britain, China and Russia - meant to buy time for talks on a final settlement of the decade-old nuclear dispute - only vaguely refers to the IAEA's investigation.
It does not, for example, say anything about the U.N. agency's repeated requests to visit the Parchin military base.
The IAEA suspects that Iran has carried out explosives tests relevant for nuclear bomb development at the facility southeast of Tehran, possibly a decade ago. Iran denies this and has so far refused to open it up for the inspectors.
The watchdog also wants to see other locations, interview officials and study relevant documents for its inquiry into what it calls the "possible military dimensions" to Iran's nuclear program, known under the acronym PMD.
A Western diplomat who closely tracks Iran developments but is not from one of the six powers - known as P5+1 as they group the five permanent U.N. Security Council members plus Germany -said the Geneva agreement "almost totally neglects" this issue.
"Do we take the P5+1's relative silence on PMD as sign that it will only get lip service now and that the past is the past?" the envoy said.
"Or is it simply a sign that we need to calm the situation now in the present, thereby build some confidence, and then they will help ensure PMD and other past issues are fully addressed before this file is declared resolved?"
The Vienna-based IAEA has been investigating accusations for several years that Iran may have coordinated efforts to process uranium, test explosives and revamp a missile cone in a way suitable for a nuclear warhead.
Iran says such claims are baseless and forged.
NO "ANYTIME, ANYWHERE" IN IRAN
As with the big power diplomacy, the parallel IAEA-Iran talks started yielding results only after the election of relative moderate Hassan Rouhani as Iran's president last June.
Under an agreement reached two months ago as the powers were reaching their own deal, the agency has already visited a heavy water production plant in Iran and is expected to soon go to a uranium mine.
However, those first steps do not go to the heart of the IAEA's investigation, and Western diplomats will closely watch an Iran-IAEA meeting in Tehran on January 21 to see whether the two sides can agree more substantive measures.
The Geneva deal says the powers and Iran will set up a joint commission that will work with the IAEA "to facilitate resolution of past and present issues of concern" - seen as code for the IAEA's investigation into suspected bomb research.
However, some experts suggest that the powers may be more concerned with obtaining an agreement to limit future Iranian nuclear enrichment than with helping the IAEA get to the bottom of research and tests Iran may have carried out in the past.
Mark Hibbs, of the Carnegie Endowment think-tank, said it was possible that they, in the interest of quickly concluding a final deal, "might strongly urge the IAEA to accept what it would consider less than satisfactory demonstration by Iran" in response to suspicions about its past activity.
Jofi Joseph, until October a director for non-proliferation on the White House National Security Council staff, said the powers may be tempted to set past PMD issues aside and focus on limits to Iran's future nuclear bomb breakout capability.
"There may be an implicit preference by the P5+1 to sweep the weaponisation issue under the rug," he wrote in a commentary last week for Harvard University's Belfer Center for Science and International Affairs.
"It is always difficult to prove a negative and, even if Iran significantly expanded access to IAEA inspectors ... doubts likely would persist that Iran was still hiding something."
In Iraq after the 1991 war, the IAEA acted under the authority of a U.N. Security Council resolution giving inspectors carte blanche "anytime, anywhere" authority, former IAEA Director General Mohamed ElBaradei said.
"From an inspector's perspective, this sounded idyllic," he wrote in his 2011 book the Age of Deception. "But it worked only because Iraq was a freshly defeated country ... No other country would have accepted such conditions."
(Editing by Peter Graff)