Thomas Dinanno, undersecretary of state for arms control and international security, said he has “not been in any discussions” where U.S. testing of nuclear weapons in the atmosphere has been under consideration.
“We’re still assessing,” Dinanno said in testimony Tuesday to the Senate Foreign Relations Committee. “We’ve made no decision specifically on how or what any testing program would look like.”
Late in October, President Donald Trump said in a social media announcement the United States would test nuclear weapons “on an equal basis” with other countries, and has since not clarified whether he meant explosive nuclear tests or not. The U.S. stopped testing nuclear weapons aboveground and underwater in 1963 through the Limited Test Ban Treaty, along with the U.K. and the then-Soviet Union. The U.S. has not tested nuclear weapons at full yield since 1992 in a self-imposed moratorium that roughly mirrors the provisions of the Comprehensive Test Ban Treaty (CTBT), which Congress has not ratified.
Dinanno was responding to a question by Sen. Jacky Rosen (D-Nev.), whose state is home to the Nevada National Security Site (NNSS), on the State Department’s position on explosive nuclear testing.
“We have made millions of billions of dollars of investments in radio, graphic and other technology, using math, using physics, using science, to be sure that we ensure the integrity of our nuclear arsenal,” Rosen said. “And I can tell you that in our U1a tunnel, and the radiographic things that we have there, and the new kinds of technology we have, we have adequately, without explosive testing, ensured that the capabilities of our nuclear stockpile.”
Dinanno continued to say that “I have not been in any discussions” where “atmosphere and open atmosphere testing has been under consideration.”
“The Chinese and Russian programs are underground,” Dinanno said. “They are at yields that I can’t talk too much about in this open hearing, but for example, the Chinese underground testing program would be in the hundreds of tons,” but “no discussions would in any way talk about winds or down range. That is, I’ve heard nothing to that effect.”
However, Dinanno concluded by saying he thinks it’s “extremely important to understand” Russia and China are testing “at yield.” By that, he means both countries are conducting nuclear tests that produce a self-sustaining, supercritical chain reaction instead of the CTBT-compliant subcritical, zero-yield experiments the National Nuclear Security Administration conducts at NNSS. There chemical explosives are used to shock nuclear materials like plutonium in a confined environment, but the quantity of nuclear material and the chemical release of the reaction is too small for a nuclear reaction to begin the way it would in a critical nuclear test.
“That creates intolerable disadvantage to the United States by not testing,” Dinanno added, to which Rosen said she disagrees.
Dinanno publicly revealed in late February that China conducted a secret explosive nuclear test in 2020.