Those Reassuring Russians

"None of the U.S. officials would confirm the weight of the seizure or its quality, but Merabishvili said it was about 3.5 ounces of uranium enriched by more than 90 percent.

Uranium enriched at 90 percent is weapons grade.

A nuclear bomb of a design similar to the one exploded over Hiroshima in 1945 would require about 110 pounds of uranium enriched at over 90 percent, according to Matthew Bunn, a senior research associate who focuses on nuclear theft and terrorism at Harvard University’s Kennedy School of Government. Bunn said that a more sophisticated implosion type nuclear bomb would require 33 to 40 pounds.

According to an IAEA database, there have been 16 previous confirmed cases in which either highly enriched uranium or plutonium have been recovered by authorities since 1993.

Russian cooperation ‘critical’
In most cases the recoveries have involved smaller quantities than the Tbilisi case. But in 1994, 6 pounds of highly enriched uranium intended for sale were seized by police in the Czech Republic. In 2003, Georgian border guards using detection devices provided by the United States caught an Armenian man with about 5 ounces of HEU, according to the State Department.

Fleming said examples of stolen or missing bomb-grade nuclear material, including highly enriched uranium and plutonium, are rare and troubling.

David Albright, a former U.N. weapons inspector and head of the Washington-based Institute for Science and International Security, said that lacking help from Russia, the CIA may be looking to other allies to help identify who has access to lost nuclear material.

“Russian cooperation in answering these questions is critical, but it has not been forthcoming,” he said. “One way to identify who is active in trading these materials is to conduct sting operations.” "