In a cooperative effort involving Britain and Georgia, the United States removed 4.3 kilograms of highly enriched uranium (HEU) and 0.8 kilograms of spent fuel from a former Soviet research reactor in Tbilisi, Georgia, on April 24. Under "Operation Auburn Endeavor," the nuclear materials were transported to the United Kingdom Atomic Energy Authority at Dounreay in Scotland, where most of them will be used for medical purposes and the rest will be stored and eventually reprocessed. The operation, funded by the Defense Department's Cooperative Threat Reduction (CTR) program, marks the second time that the United States has removed vulnerable fissile materials from the former Soviet Union. (Under "Operation Sapphire" in 1994, the United States transported and secured 600 kilograms of HEU from Kazakhstan).Although there were no known attempts by foreign entities to obtain the Georgian HEU, the United States was concerned that the nuclear materials might fall into the wrong hands given the political instability in the Caucasian region and Georgia's proximity to Iran. The fissile materials in question could have contributed to a potential nuclear weapons program, but would not, in themselves, have been enough to fabricate a nuclear explosive device.