VIENNA The U.N. atomic watchdog is set to issue a report this week with detailed intelligence pointing to research and experiments in Iran to develop the technology and skills needed to make nuclear bombs, Western diplomats say.
The following addresses questions about the report:
WHY IS THE IAEA PUBLISHING ITS FINDINGS NOW?
The International Atomic Energy Agency has voiced increasing disquiet about possible military dimensions to Iran's nuclear program in a series of quarterly reports. They have lent independent weight to Western allegations that Tehran is seeking the means to build atomic bombs behind the facade of a declared civilian nuclear energy program.
IAEA Director General Yukiya Amano said in September he would soon give the reasons for why he was "increasingly concerned" that Iran may be developing a nuclear missile.
Diplomats say Amano, who has taken a tougher approach on the Iran nuclear file than his predecessor Mohamed ElBaradei, sees it as his duty to inform member states about the issue, even though the agency's technical findings may have far-reaching political implications.
"We have heard many times that member states want more information and we are trying to the extent possible," Amano, a veteran Japanese diplomat, told Reuters in August.
IAEA officials have often complained that Iran has refused, for at least three years, to seriously answer the agency's questions about accusations of illicit nuclear work.
"If the IAEA sees activities which could be associated with nuclear weapon design -- with or without nuclear material -- it should act," said former U.N. nuclear inspections chief Olli Heinonen, now a senior fellow at Harvard University.
WHAT WILL THE REPORT SAY?
Western diplomats and nuclear experts expect the document, tentatively scheduled to be submitted to IAEA member states on Wednesday, to give a wide-ranging picture of research and development work that clearly suggests military nuclear aims.
For several years the IAEA has been investigating Western intelligence reports indicating that Iran has coordinated efforts to process uranium, test high explosives and revamp a ballistic missile cone to accommodate a nuclear warhead.
"The activities of Iran, for example, with high explosives and neutron physics experiments are alarming. They do exist, and the question is now what the purpose of those activities is," Heinonen told Reuters in an e-mail.
Diplomats said the data indicating military-oriented activities would be covered in an annex of more than 10 pages to the main report, including evidence of activities that would only make sense for weapons purposes.
It will give new information about allegations the Vienna-based agency has briefly voiced concern about in the past -- including research to develop a nuclear bomb trigger, uranium metallurgy and explosives testing, they said.
Sources familiar with the document said it would support allegations that Iran built a large steel container for the purpose of carrying out tests with high explosives applicable to nuclear weapons, and also that Iran conducted computer modeling of a nuclear weapon.
Intelligence provided to the IAEA shows that Iran has mastered the critical steps needed to build an atomic weapon, receiving crucial technical assistance from foreign scientists, The Washington Post reported on Sunday.
But the IAEA is likely to stop short of saying explicitly that Iran is developing nuclear bombs, as Western officials would want it to.
"It is important to note that this is R&D (research and development) and not actually work to construct a warhead with nuclear material," said U.S.-based Analyst Peter Crail of the Arms Control Association, an advocacy and research group.
WHERE DOES THE INFORMATION COME FROM?
The IAEA has said in previous reports that the information it has obtained about the possible underlying military nature of Iran's nuclear program is extensive and comprehensive, and also "broadly consistent and credible."
It said in its last report in September that it continued to receive such information, making clear it was recent.
It has not named the countries which have supplied the data, but it is widely believed to come from the United States, its European allies such Britain, France and Germany as well as Israel, and through the agency's own investigations.
Ali Vaez, an Iran expert at the Federation of American Scientists think tank, said the most important source in the past of the agency's information consisted of a collection of electronic files stored in the so-called "Laptop of Death," shown by U.S. intelligence officials to the IAEA in 2005.
"These include thousands of pages of documents, diagrams and videos brought to Turkey by the wife of an Iranian," Vaez said. The documents included were designs for nuclear warheads and diagrams of underground testing sites, he said.
A U.S.-based think-tank, the Institute for Science and International Security, said in a 2009 report that the Iranian was recruited by German intelligence but that his activities had been discovered by Iranian authorities. One of his last acts before his arrest was to pass nuclear information to his wife, ISIS said, and intelligence officials assumed he was now dead.
The IAEA has also received material about illegal procurements as well as about travels and communications of Iranian officials and scientists, Vaez said.
DOES IT MEAN IRAN IS GETTING CLOSER TO HAVING A BOMB?
Not necessarily. Western diplomats and analysts say they don't know whether Iran will ultimately choose to build nuclear weapons, even though it is making progress on technology needed for that purpose, including uranium enrichment and missiles.
Some analysts believe Iran seeks now only to be a "virtual" nuclear power -- able to make bombs swiftly if needed to safeguard its Islamist leadership from major foes, the United States and Israel, by deterring them from attack, and to further its longtime ambition to be the Middle East's pre-eminent power.
Experts differ on when Iran might be able to acquire a nuclear arsenal, but many believe Iran is still a few years away from potentially having nuclear missiles.
Iran's move last year to make uranium refined to a fissile purity of 20 percent -- compared with 3.5 percent normally used to fuel power plants -- raised alarm in the West as this moved it closer to weapons-grade material of 90 percent.
Even if Iran were to produce bomb-grade uranium, it would also have to transform it from gaseous into metal form, squeeze it into the nose cone of a missile, fit it with a chain reaction-triggering device and surround the fissile material with fast explosives and high-precision detonators.
U.S. spy services estimated in 2007 that Iran had halted outright "weaponization" work four years previously, but also said it continued efforts to master technology applicable to yielding nuclear explosives.
WHAT IS IRAN LIKELY TO SAY ABOUT REPORT?
The Islamic Republic has repeatedly dismissed as forged and baseless the intelligence fed to the IAEA suggesting that it is trying to develop a nuclear missile.
One of the world's largest oil producers, Iran says it needs to enrich uranium to fuel a planned network of nuclear power stations as an alternative source of electricity for a rapidly growing population, and also that it would be a strategic mistake for the Islamic Republic to build nuclear weapons. It also says such arms are banned under Islam.
But Tehran's history of concealing sensitive nuclear activity, continued restrictions on IAEA inspections and its refusal to suspend work that also can also yield atomic bombs have drawn four rounds of U.N. sanctions, as well as separate punitive steps by the United States and European Union states.
WHAT IMPACT COULD REPORT HAVE?
Western diplomats hope the report will help to ratchet up the pressure on Tehran to finally start addressing international concerns about its atomic activities and enter serious talks on resolving the long-running nuclear row.
But Iran has already before the report's publication dismissed its content as fabricated, suggesting the document will not force Tehran to curb its nuclear work or be fully transparent with U.N. inspectors. Stepping up its defiant rhetoric in the face of outside pressure, it has poured scorn on speculation that Israeli might soon attack its atomic sites.
It may further stoke tension in the Middle East: Israel test-fired a missile last week amid a heightened public debate in the Jewish state over the possibility of pre-emptive Israeli strikes on Iran's nuclear facilities.
With Iran showing no sign of backing down, the United States and its European allies could use the IAEA's findings to try to impose more sanctions on Tehran, even if Russian and Chinese reluctance may hinder any new U.N. sanctions.
Western states are expected to press for a resolution at a November 17-18 meeting of the IAEA's 35-nation governing board to at least condemn Iran over its nuclear activities.
But Russian and Chinese opposition makes it unlikely the board will decide to report Iran to the U.N. Security Council, as happened in 2006.