Bunn also recommends the HEU be mixed with low-grade uranium which, while making the uranium unusable in bombs, would still be useful as power-reactor fuel.

The report comes on the heels of efforts by the U.S. to improve U.S.-Russia relations on the monitoring of nuclear weapons material.

In October, Secretary of Energy Bill Richardson signed an agreement with Russia inaugurating a joint center to monitor the use of nuclear materials.

But Bunn argues that more comprehensive measures are needed.

"Although the U.S. has a wide range of specific programs on different aspects, much more needs to be done if we're going to avoid a possible proliferation catastrophe," he said.

Bunn said he attributes the fact that such a catastrophe has not yet occurred to many of the parties involved.

"First, we've been lucky," he said. "Second is the amazing patriotism and devotion of the vast majority of nuclear scientists and technicians in Russia."