"I'm not prepared to forever give up our right to [test] with the circumstances that exist in the world today," he said during a discussion at the Carnegie Endowment for International Peace Nuclear Policy Conference.
Treaty skeptics have also questioned whether treaty states might be able to cheat and conduct low-yield nuclear tests in secret.
Tauscher responded to those concerns by highlighting U.S. detection capabilities and those put in place through the Preparatory Commission for the Comprehensive Test Ban Treaty. The global lattice of CTBT detection sites is expected to be 90 percent complete before the start of 2013. Today, the network boasts 265 certified monitoring and laboratory installations.
"Taken together, these verification tools would make it difficult for any state to conduct nuclear tests that escape detection," the diplomat said.
She rejected the idea that last year's deliberations on New START hindered chances for CTBT ratification on Capitol Hill.
"I know that the conventional wisdom is that the ratification of New START has delayed or pushed aside consideration of the CTBT," according to Tauscher. "I take the opposite view."
She said that before debate began on the arms control deal "there was not a lot of muscle memory on treaties, especially nuclear treaties, in the Senate." Now, though, the chamber is better versed on such international pacts.
With New START ratified, the administration is "in a stronger position to make the case for the CTBT on its merits," Tauscher told the audience.
She praised the National Nuclear Security Administration's Stockpile Stewardship Program, which works without conducting test detonations to ensure the country's nuclear weapons would perform as expected.
Physicists and engineers inspect weapons in the arsenal to monitor the effects of aging, and carry out computer simulations to anticipate problems and devise fixes. They can then repair or remanufacture aging components without altering warhead design details.
"Our current efforts go a step beyond explosive testing by enabling the labs to anticipate problems in advance and reduce their potential impact on our arsenal -- something that nuclear testing could not do," according to Tauscher.
The diplomat also noted that the National Academies of Science is expected to soon release a separate assessment that many expect will support the pact's ratification.