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Proliferation Experts Say Technology in Place to Verify Nuclear Test Ban Compliance


Ola Dahlman

Two top proliferation experts at a AAAS briefing called on U.S. lawmakers to reevaluate the Comprehensive Test Ban Treaty (CTBT) as a means to control nuclear proliferation.

Learn more about the AAAS Center for Science, Technology, and Security Policy.

Speaking 10 years after the United States Senate failed to ratify the treaty prohibiting nuclear test explosions, Ola Dahlman, an expert with the Preparatory Commission of the CTBT, and David Hafemeister, a visiting fellow at the Arms Control Association, said that technological innovations have increased the ability for governments to verify that other nations are not testing weapons—a previous sticking point for U.S. lawmakers.

Dahlman, a seismologist who served as chairman during the first 10 years of the Working Group on Verification for the CTBT Preparatory Commission, said that since the U.S. signed the CTBT in 1996 but failed to ratify it three years later, significant innovations have been made in the four main technologies used to detect the testing of nuclear weapons—seismology (ground vibrations), hydroacoustic (water vibrations), infrasound (atmospheric vibrations), and radionuclide (elements in the atmosphere).

Dahlman said if the requisite nations ratify the treaty and the global nuclear testing monitoring stations are fully activated, the Comprehensive Test Ban Treaty Organization through its international data center based in Vienna, Austria, would be able to detect as little as a 0.1 kiloton explosion in most parts of the world, and a 0.01 kiloton explosion in many critical regions.

While the United States raised legitimate concerns in 1999 about the ability to detect small nuclear tests around the world, we now have much more sensitive technology to allay those apprehensions, said Dahlman.


David Hafemeister

While the United States is not alone in its failure to ratify the CTBT, Hafemeister said action by the U.S. Senate could reinvigorate international debate surrounding non-proliferation and encourage other nations that have signed but not ratified the treaty-- China, Egypt, Indonesia, Iran, and Israel—to do so.

Referring to comments made by U.S. President Barack Obama during his 2008 election campaign, Hafemeister believes Obama will urge the U.S. Senate to reexamine the treaty, bringing the U.S. on board into the CTBT regime by 2010 , or after the next (mid-term) elections.

In 1999, the U.S. Senate also raised concerns about the nations aging nuclear stockpiles, arguing that testing might be required to verify that our weapons are functional. In addition, many weapons experts have called for a redesign for U.S. nuclear weapons through the Reliable Replacement Warhead (RRW) program, updating the national arsenal for post-Cold War scenarios.

While concerns about certifying the aging American nuclear arsenal are legitimate, experts have continually assured us that the weapons are up to date, said Hafemeister, who is professor emeritus of physics at California Polytechnic State University in San Luis Obispo, Calif.

Co-sponsored by the AAAS Center for Science, Technology, and Security Policy and the Center for Media and Security, the 8 April luncheon for reporters was held at the Fairmont Hotel in Washington, D.C., as part of an ongoing collaboration to bring scientists, policymakers, and reporters together on pressing issues of national security and defense.

Benn Tannenbaum, CSTSP associate program director, said that as proposals and debates surrounding a test ban treaty have evolved, so has the science necessary to carry out its verification.

Obama has made it clear on several occasions that the treaty is in the interest of the United States and the world, said Tannenbaum. And part of the presidents case to Congress is going to be based on science and our ability to verify that nations will not be able to test without the world knowing.

The CTBT was opened for signatures by the United Nations General Assembly in September 1996 and was signed by practically all the member nations; currently, there are 180 signatories to the treaty, and 148 of these have ratified it. The treaty would go into force 180 days after all of the nations who had nuclear weapon technology—including the United States—ratify it. Once the treaty is entered into force, all signatory nations are forbidden to carry out nuclear testing, and must refrain from allowing other nations to carry out testing under their jurisdiction.

For example, Dahlman said that when North Korea tested its first nuclear weapon in 2006, scientists had access to seismic data in around 15 minutes that detected an explosion, and U.S. radionuclide data within one day and CTBT data later, that allowed nations to determine it was a nuclear explosion.

Dahlman, who worked on a report to be released in June, said that there will be 337 monitoring stations around the world in the final system. While the technology to detect nuclear testing is vastly improved compared to 10 years ago, nothing is a guarantee, he said.

Dahlman added that opponents to the treaty say that since there is no guarantee to be able to detect every explosion, nations—including the U.S.—should be wary of ratifying it.

Nations need to balance the risk, and ask if they are better off joining the treaty or remaining outside the regime, he said. It is ultimately a political decision, not one of science.