VIENNA — After more than a decade of working behind layers of front companies and in hidden laboratories, Iran appears to be in the late stages of developing the capacity to build a nuclear bomb.
Iran insists that like many countries it is only building commercial nuclear reactors to generate electricity for homes and factories. "Iran's efforts in the field of nuclear technology are focused on civilian application and nothing else," President Mohammad Khatami said on state television in February. "This is the legitimate right of the Iranian people."
But a three-month investigation by The Times -- drawing on previously secret reports, international officials, independent experts, Iranian exiles and intelligence sources in Europe and the Middle East -- uncovered strong evidence that Iran's commercial program masks a plan to become the world's next nuclear power. The country has been engaged in a pattern of clandestine activity that has concealed weapons work from international inspectors. Technology and scientists from Russia, China, North Korea and Pakistan have propelled Iran's nuclear program much closer to producing a bomb than Iraq ever was.
No one is certain when Iran might produce its first atomic weapon. Some experts said two or three years; others believe the government has probably not given a final go-ahead. But it is clear that Iran is moving purposefully and rapidly toward acquiring the capability.
Among the findings:
* A confidential report prepared by the French government in May concluded that Iran is surprisingly close to having enriched uranium or plutonium for a bomb. The French warned other governments to exercise "the most serious vigilance on their exports to Iran and Iranian front companies," according to a copy of the report provided by a foreign intelligence service.
* Samples of uranium taken by U.N. inspectors in Iran in June tested positive for enrichment levels high enough to be consistent with an attempt to build a nuclear weapon, according to a foreign intelligence officer and an American diplomat. The Reuters news service first reported the possibility that the material was weapons-grade last month.
* Iran is concealing several weapons research laboratories and evidence of past activity at a plant disguised as a watch-making factory in a Tehran suburb. In June, U.N. inspectors were refused access to two large rooms and barred from testing samples at the factory, called the Kalaye Electric Co.
* Tehran secretly imported 1.8 tons of nuclear material from China in 1991 and processed some of it to manufacture uranium metal, which would be of no use in Iran's commercial program but would be integral to weapons production.
* As early as 1989, Pakistani generals offered to sell Iran nuclear weapons technology. Abdul Qadeer Khan, a Pakistani nuclear scientist regarded by the United States as a purveyor of nuclear secrets, has helped Iran for years. "Pakistan's role was bigger from the beginning than we thought," said a Middle Eastern intelligence official.
* North Korean military scientists recently were monitored entering Iranian nuclear facilities. They are assisting in the design of a nuclear warhead, according to people inside Iran and foreign intelligence officials. So many North Koreans are working on nuclear and missile projects in Iran that a resort on the Caspian coast is set aside for their exclusive use.
* Russian scientists, sometimes traveling to Iran under false identities and working without their government's approval, are helping to complete a special reactor that could produce weapons-grade plutonium. Moscow insists that it is providing only commercial technology for the civilian reactor under construction near the Persian Gulf port of Bushehr, an assertion disputed by Washington.
* In recent months, Iran has approached European companies to buy devices that can manipulate large volumes of radioactive material, technology to forge uranium metal and plutonium and switches that could trigger a nuclear weapon. European intelligence sources said Tehran's shopping list was a strong indication that Iran has moved to the late stages of weapons development.
A nuclear-armed Iran would present the United States with a difficult political and military equation. Iran would be the first avowed enemy of Israel to possess a nuclear bomb. It also has been labeled by the Bush administration as a state sponsor of international terrorism.
Iranian nuclear weapons could shift the balance of power in the region, where Washington is trying to establish pro-American governments in Afghanistan and Iraq. Both of those nations border Iran and are places where Tehran wants to exert influence that could conflict with U.S. intentions, particularly in Iraq.