By Jonathan Landay and Simon Lewis
WASHINGTON, March 24 (Reuters) - A senior State Department official on Tuesday said the U.S. still is assessing how to implement President Donald Trump’s order to resume U.S. nuclear weapons tests, but he did not rule out a resumption of full-scale underground explosive tests.
“We’ve made no decision specifically on how or what any testing program would look like,” Undersecretary of State for Arms Control and International Security Thomas DiNanno testified to the Senate Foreign Relations Committee.
Arms control advocates warn that a U.S. resumption of underground explosive tests could collapse the global non-proliferation system because Russia, China and other countries would follow suit. The last such U.S. test took place in 1992.
DiNanno was asked by Democratic Senator Jacky Rosen of Nevada, where the U.S. nuclear test site is located, how a directive that Trump issued in October for nuclear weapons tests “on an equal basis” with other countries was being implemented.
Trump issued the order just before meeting Chinese President Xi Jinping in what some experts saw as an unsuccessful attempt to pressure Xi to drop his refusal to open talks on Beijing’s growing nuclear arsenal.
DiNanno reiterated U.S. charges that Russia and China secretly have conducted explosive nuclear underground tests, allegations that Moscow and Beijing deny and some experts have challenged.
“The Chinese and Russian programs are underground. They are at yields that I can’t talk too much about in this open hearing,” he said, adding that “the Chinese underground testing program would be in the hundreds of tons.”
“This creates intolerable disadvantage to the United States not testing,” DiNanno said, adding that internal administration deliberations have not included a resumption of atmospheric tests, which the U.S. last conducted in 1962.
Since 1994, the U.S. has ensured that its nuclear arsenal is safe and reliable by replacing underground explosive testing with a multi-billion dollar “science-based approach” of super computer modeling and other advanced tools.
Rosen noted that using those methods, the U.S. has ensured “the capabilities of our nuclear stockpile,” a certification made annually by the Pentagon and Department of Energy, the caretaker of the U.S. arsenal.
Some experts, however, have called for a resumption of underground tests to ensure that aging U.S. nuclear weapons function properly.
China’s last official underground test blast was in 1996 and Russia’s in 1990.
Like the U.S., China signed but has not ratified the 1996 Comprehensive Test Ban Treaty (CTBT). Russia revoked its ratification in 2023. Under international law, the three countries as signatories still are obligated to uphold the pact.
(Reporting by Jonathan Landay and Simon Lewis; Editing by Franklin Paul and Cynthia Osterman)
