The United States, working with Kazakhstan and Russia, spent $150 million on the project -- a tiny amount of money given the threat posed by the material required for one nuclear weapon falling into the hands of criminals or terrorists, let alone enough material for a dozen weapons.

But the hard work to secure the site couldn't have been accomplished without America's local Kazakh partners. Four 10-man Kazakh crews worked year round for seven years to dig out, drill into, and ultimately fill the former nuclear test chambers with the special cement. They lived in modified 40-foot cargo containers and braved extreme conditions. One frigid day on the steppe, a work crew had to take a blow torch to the side of their frozen water tank truck just to melt a supply of drinking water. The Kazakh work crews were guided by Russian nuclear scientists and U.S. experts from the Pentagon's Defense Threat Reduction Agency and the Los Alamos National Laboratory, who traveled to the site every four to six weeks, also braving difficult conditions.

U.S. assistance also went to help the Kazakh government enforce its exclusion zone, pay for fences, patrol vehicles, aerial surveillance drones, and even seismic sensors disguised as rocks to alert security forces to the presence of an intruder. These measures have worked. No scavenger activity has been observed at the site since 2009.

Related initiatives to secure other types of nuclear material are ongoing around the world -- and more will be required. The work at Degelen Mountain is a model of how the international community, and Republican and Democratic administrations alike, is cooperating to reduce the nuclear threat. The world is safer for this effort, and it deserves to be recognized.