From The New York Times, November 27, 2009, by David E. Sanger from Washington, and William J. Broad from New York:
The director general of the United Nations nuclear watchdog declared in unusually blunt language on Thursday that Iran had stonewalled investigators about evidence that the country had worked on nuclear weapons design, and that his efforts to reveal the truth had “effectively reached a dead end.”
The comments by the official, Mohamed ElBaradei, came four days before he is to leave office after 12 years at the head of the International Atomic Energy Agency. His remarks refocus attention on Iran’s alleged work on weapons design at the moment that the West is debating how to respond after Tehran backed away from a commitment it made in early October to temporarily send much of its nuclear fuel abroad.
Dr. ElBaradei’s remarks also came as President Obama’s end-of-year deadline is approaching to reassess whether the United States should move toward what Secretary of State Hillary Rodham Clinton has termed “crippling sanctions” on Iran.
...Dr. ElBaradei’s statement was a sharp departure in tone, and a tacit acknowledgment that his behind-the-scenes effort to broker a deal had collapsed.
...But the central issue in the Iran investigations has been the evidence suggesting that Iran conducted some level of research on weapons. An American intelligence assessment, published two years ago, contended that Iran ceased that work in 2003; intelligence agencies in Britain, France, Germany and Israel, examining the same evidence, have concluded that the work has resumed, or never stopped.
In October, parts of a confidential analysis written by senior staff members of the watchdog agency were leaked. The analysis concluded that Iran had acquired “sufficient information to be able to design and produce a workable” atom bomb. The report’s conclusions went beyond Dr. ElBaradei’s public positions, and even those taken by the United States and several governments.
The analysis drew a picture of a complex program, run by Iran’s Ministry of Defense, “aimed at the development of a nuclear payload to be delivered using the Shahab 3 missile system,” Iran’s medium-range missile, which can strike the Middle East and parts of southern Europe.
That analysis, and others like it, draw on years of clues and scraps of information gathered in Iran and from intelligence agencies around the world. For instance, atomic inspectors have found signs that Iran has done extensive research on high-voltage detonators, explosive lenses for bomb detonation and re-entry vehicles for missiles that can cushion nuclear warheads as they streak earthward.
The inspectors also found evidence that a Russian scientist had helped Iran conduct complex experiments on how to detonate a nuclear weapon. They said they believed he acted on his own as an adviser on experiments described in a lengthy document the agency obtained. Officials have described the original, in Persian, as a detailed narrative of experiments aimed at achieving the perfectly timed compression of nuclear fuel to squeeze it into supercritical mass, which initiates a nuclear blast.
In 2006, the agency released a report saying Iran had obtained from the global black market a document “related to the fabrication of nuclear weapon components.” The previous year it told of the market’s offering to help Iran shape uranium metal into “hemispherical forms,” which Western experts say are needed to make nuclear bomb cores.
Also in 2005, European and American officials told of an Iranian laptop computer that held studies for crucial features of a nuclear warhead, including a telltale sphere of detonators to trigger an atomic explosion. The documents specified a blast roughly 2,000 feet above a target — considered high enough for a nuclear detonation to maximize the damage below.