NUCLEAR WEAPONS Iranian technology linked to Pakistan

Iran has provided to international experts documents covering 17 years.
WASHINGTON POST
VIENNA -- Evidence discovered in a probe of Iran's secret nuclear program points overwhelmingly to Pakistan as the source of crucial technology that put Iran on a fast track toward becoming a nuclear weapons power, according to U.S. and European officials familiar with the investigation.
The discoveries prompted a decision by Pakistan two weeks ago to detain three of its top nuclear scientists for several days of questioning, with U.S. intelligence experts allowed to assist, the officials said. The scientists haven't been charged with any crime, and Pakistan continues to insist that it never wittingly provided nuclear assistance to Iran or anyone else.
Documents provided by Iran to U.N. nuclear inspectors since early November have exposed the outlines of a vast, secret procurement network that successfully acquired thousands of sensitive parts and tools from numerous countries over a 17-year period. Though Iran has not directly identified Pakistan as a supplier, Pakistani individuals and companies are strongly implicated as sources of key blueprints, technical guidance and equipment for a pilot uranium-enrichment plant that was exposed by Iranian dissidents 18 months ago, government officials and independent weapons experts said.
Long-standing concern
American presidents since Ronald Reagan worried that Iran might seek nuclear weapons, but U.S. and allied intelligence agencies were unable to halt Iran's most significant nuclear acquisitions, or even to spot a major nuclear facility under construction until it was essentially completed.
Although the alleged transfers occurred years ago, suggestions of Pakistani aid to Iran's nuclear program have further complicated the relationship between the United States and Pakistan, a key ally in the war against terrorism.
In documents and interviews with investigators of the International Atomic Energy Agency, Iranian officials have offered detailed accounts of how they obtained sensitive equipment from European, Asian and North American companies. Much of the equipment was routed through a trans-shipment hub in the Persian Gulf port city of Dubai to conceal the actual destination, according to officials familiar with Iran's disclosures.
China and Russia also made significant contributions to the Iranian program in the past, IAEA documents show. Both countries were the focus of a long-running U.S. campaign to cut off nuclear assistance to Iran.
Difficulties of detection
The disclosures about Pakistan offer a striking illustration of the difficulties faced by U.S. officials in trying to detect and interdict shipments of contraband useful in making weapons of mass destruction. Iran appears to have obtained the equipment by exploiting a gray zone of porous borders, middlemen, front companies and weak law enforcement where the components of such weapons are bought and sold.
Iran's pilot facility, which is now functional, and a much larger uranium-enrichment plant under construction next door are designed to produce enough fissile material to make at least two dozen nuclear bombs each year. The United States has sought for years to prevent Iran from joining the club of nuclear weapons states.
In a new finding, sophisticated laboratory tests by the IAEA detected traces of Soviet-made highly enriched uranium at Iran's Kalaye nuclear facility, a former testing center for uranium-enrichment equipment, knowledgeable officials said. Several distinct types of enriched uranium have been found at the site, the officials added. Although there are other possible explanations, the finding could indicate that Iran obtained some fissile material from a former Soviet state to use in testing its equipment, the officials said.
Uranium-processing machines
By far the most valuable assistance to Iran came from still-unnamed individuals who provided top-secret designs and key components for uranium-processing machines known as gas centrifuges, the officials said.
Centrifuges are technologically complex machines that spin at supersonic speeds to extract the small amounts of fissile material present in natural uranium. Uranium that has been enriched at lower levels is typically used as fuel in nuclear power plants, while a more concentrated product known as highly enriched uranium is used in nuclear submarines, research reactors and nuclear weapons.
The blueprints, which the IAEA has reviewed, depict a type of centrifuge that is nearly identical to a machine used by Pakistan in the early years of its nuclear program, according to U.S. officials and weapons experts familiar with the designs.