Twenty years ago, a popular movement in Soviet-controlled Kazakhstan forced Moscow’s communist regime to halt nuclear weapons testing at proving grounds in their homeland where more than 456 explosions had contaminated the land and its people. Soviet leader Mikhail Gorbachev would authorize only one more test (in Russia) and then declare a moratorium in October 1991, prompting U.S. legislators to initiate a U.S. test moratorium. The last U.S. nuclear test explosion was conducted on September 23, 1992.

Just four years later, the world’s nations concluded the Comprehensive Test Ban Treaty (CTBT) to prevent proliferation and help end the nuclear arms race. President Bill Clinton was the first of 182 national leaders that have signed the treaty, yet the CTBT must still be ratified by the United States and eight other hold-out states before it can formally enter into force.

On the occasion of the first International Day against Nuclear Tests on August 29, President Barack Obama should reiterate his 2009 pledge to pursue reconsideration and ratification of the CTBT. The United States should also use the upcoming September 23 foreign ministerial meeting at the UN on the CTBT to rally support for the treaty. American action on the treaty would prompt a chain reaction of ratifications by the eight other hold-out states, including China and India, and bolster the global drive to prevent proliferation.

A growing list of bipartisan national security leaders agree that by ratifying the CTBT, the United States can strengthen its security by limiting the ability of other states, such as China or even Iran, to proof test sophisticated nuclear weapons designs that could pose a threat to U.S. and international security.

They also agree that after 1,030 U.S. nuclear test explosions, there is simply no technical or military rationale for resuming testing. Contrary to myth, the United States has never relied on nuclear testing to ensure that proven warhead designs still work, but rather to perfect new types of nuclear bombs, which the U.S. military no longer needs nor wants.

Nevertheless, some U.S. senators—many of whom have not examined the topic in detail—are reluctant to give up the testing option. But since the Senate’s brief and partisan rejection of the CTBT in 1999, there have been significant advances in U.S. programs to extend the life spans of proven warhead designs and nuclear test monitoring that should address earlier concerns that led many senators to vote no. As former U.S. Secretary of State George Shultz stated on April, 17, 2009, his fellow Republicans “might have been right voting against it some years ago, but they would be right voting for it now, based on these new facts.”

Since 1994, each warhead type in the U.S. nuclear weapons arsenal has been determined to be safe and reliable through a rigorous certification process. Life Extension Programs (LEPs) have refurbished and modernized major warhead types. The September 2009 study by the JASON independent technical review panel concluded that the “lifetimes of today’s nuclear warheads could be extended for decades, with no anticipated loss in confidence.” JASON found “no evidence that accumulation of changes incurred from aging and LEPs have increased risk to certification of today’s deployed nuclear warheads.”

The Obama administration’s strong support for higher nuclear weapons laboratories’ budgets—$80 billion over the next 10 years—should also help change attitudes. Key House and Senate appropriations committees have approved the administration’s $7 billion request for fiscal 2011 nuclear weapons complex activities, a 13 percent increase from the year before. Senators of both parties should recognize that further delay of CTBT ratification would create greater uncertainty about U.S. nuclear policy that could jeopardize the emerging political consensus for higher funding to maintain the shrinking U.S. nuclear stockpile in years ahead.

The United States’ capability to detect and deter possible cheating by other countries will also be significantly greater with the CTBT than without it. The CTBT and its global monitoring network, international data center, and option for on-site inspections would augment existing U.S. national test monitoring assets.

North Korea has provided two recent real-world tests of U.S. and global monitoring capabilities. In October 2006, the treaty’s International Monitoring System (IMS) easily detected Pyongyang’s relatively low-yield (0.6 kiloton) nuclear explosion at 22 seismic stations. Telltale radioactive gases from this test were also detected by South Korea and the United States, as well as one of the international network’s radionuclide monitoring stations 4,600 miles away in Canada.

North Korea’s second nuclear test in May 2009 was detected by 61 seismic stations, which provided precise geographical information that could have been used to pinpoint an on-site inspection. However, such treaty-mandated inspections will only be available when the CTBT enters into force.

Despite powerful U.S. and international test monitoring capabilities, some skeptics worry that small-scale, clandestine tests cannot be detected with absolute certainty. This argument misses the point of verification and implies that low-yield tests are worth the high risk of getting caught. The one country that might be able to conduct low-yield testing successfully—Russia—already possesses a large and advanced nuclear weapons arsenal. Additional testing would do little to increase the threat Russia already poses.

On the other hand, countries with less nuclear test experience or design sophistication, such as China, India, Pakistan, or Iran, would be unable to conceal tests in the numbers and yields required to master more advanced warheads. Without the treaty in force, the United States does not have the option to seek short notice, on-site inspections to investigate suspicious events.

Some test ban treaty skeptics erroneously charge that because the treaty does not define “nuclear test explosion,” some states, such as Russia, believe very low-yield “hydronuclear” tests are permitted. The record is clear: the CTBT bans “any nuclear weapon test explosion or any other nuclear explosion.” As the Russian government explained to the Duma in 2000, “[F]ull-scale and hydronuclear tests with the emission of fissile energy…directly contradict the CTBT.”

Nuclear testing is a dangerous and unnecessary vestige of the past. U.S. inaction on the CTBT is self-defeating and counterproductive. The United States has neither the intention nor need to renew testing, yet its failure to ratify the CTBT undermines both U.S. leadership credibility and the United States’ ability to improve the detection and deterrence of testing by others.

Following the approval of the New Strategic Arms Reduction Treaty (START), President Obama should undertake the major high-level campaign that will be needed to push the CTBT through the Senate in 2011. And it is the Senate’s responsibility to the nation to reconsider the CTBT on the basis of an honest and up-to-date analysis of the facts and issues at stake.

Daryl G. Kimball is executive director of the Arms Control Association.