Purchases Linked N. Korean to Syria

A spokesperson at the Chinese Embassy denied any knowledge of the company and its activities.

"I am not aware of anything about the North Korean company mentioned. . . . China is steadfastly opposed to the proliferation of weapons of mass destruction and its deliveries, and it has been faithfully honoring its international obligations and responsibilities," Wang Baodong said in an e-mailed statement.

Proliferation experts say NCG used many methods to conceal the intended use of the items it was acquiring.

NCG has acted "as a trading agent or middleman, buying items through Chinese trading companies or directly from foreign companies," said David Albright, president of the Washington-based Institute for Science and International Security and an expert on the international black market for nuclear technology.

Because of its branch office in China, NCG can buy equipment from suppliers throughout the world, even in Europe and possibly in the United States, particularly if the companies have subsidiaries in China, Albright said. Moreover, export controls in China are poorly implemented and simple to evade.

Other North Korean companies with offices outside the country have bought militarily sensitive equipment from commercial vendors, including parts for making ballistic missiles, nuclear bombs and other advanced weapons, U.S. officials say. Over the years, they have bought metals used in uranium enrichment and chemical precursors for highly lethal nerve agents, the officials said.

"North Korea often works through these trading companies, which facilitate business deals and other activities overseas that earn foreign exchange for the government and especially for the top leadership. They have been very active in the past in facilitating missile sales in countries like Syria and Iran," said Larry Niksch, an expert on Asia at the Congressional Research Service.

A U.S. counterproliferation official said in an interview that North Korea typically uses "one, two or more layers" of front companies so it can plausibly deny knowledge of actual intended use. "Sometimes they can fool the supplier by saying the goods are intended for another country altogether. North Korea does this very well," said the official, who spoke on the condition of anonymity because U.S. investigations remain classified.

Over the past decade, NCG's activities have been the target of investigations spanning two continents. Its attempt to purchase hundreds of high-strength tubes from European businesses attracted the attention of the German government in 2003. The tubes were made of a highly specialized type of aluminum used in making centrifuges for uranium enrichment, but Yun, the NCG businessman, told German companies that they were destined for an aircraft factory in China, according to court documents.

Eventually, Yun -- who earlier served as the head of North Korea's United Nations delegation in Vienna, the home of the U.N. nuclear watchdog agency -- struck a deal with a Bavarian company to obtain 22 tons of British-made tubes. They were placed on an Asia-bound ship in April 2003 and made it as far as the Suez Canal before German authorities ordered the cargo seized.

A subsequent investigation by nuclear weapons experts, including several at the International Atomic Energy Agency, concluded that the tubes were not suited for aircraft. The Chinese company named by NCG as the intended user denied ordering such tubes, U.S. and European investigators said.

In court documents and interviews, German officials alleged that NCG had operated as a front company for years and had sought to buy a wide range of sensitive equipment from European firms, including oscilloscopes and other electronic gear used in making and testing nuclear detonators.