NEW YORK — Robert Floyd, executive secretary of the Comprehensive Nuclear Test Ban Treaty Organization, warned at a United Nations treaty review meeting in New York that any nuclear test by the United States, Russia or another nation would prompt others to follow. The warning came as the United Nations began its review of a separate treaty intended to prevent the spread of nuclear weapons.

"That is a spiral that we do not want to see start, because it may never be able to be stopped," Floyd said. He said the treaty's international monitoring system can detect even a relatively small nuclear weapons explosion anywhere in the world.

Late last year, both the United States and Russia threatened to resume nuclear testing. The two countries hold the world's largest nuclear arsenals. At the end of last year, President Donald Trump accused Russia and China of conducting nuclear tests and instructed the Defense Department to start testing nuclear weapons on an equal basis.

Russian Deputy Foreign Minister Sergei Ryabkov said Russia would only resume nuclear tests if Washington conducted tests first. China and Russia have said they adhere to a nuclear testing moratorium. Since 2019, the U.S. State Department has publicly expressed concerns about the activities of both China and Russia.

The Comprehensive Nuclear Test Ban Treaty was adopted in 1996. When it opened for signatures 30 years ago, more than 2,000 nuclear tests had taken place. Since then, fewer than a dozen nuclear tests have been conducted, including six by North Korea.

The treaty has not entered into force because it must be ratified by 44 specific countries, and nine of them have not yet done so. The United States, China, Iran, Egypt and Israel have signed but not ratified the treaty. India, Pakistan and North Korea have neither signed nor ratified it. Russia signed and ratified the treaty but revoked its ratification in 2023. The United Nations review is taking place against the backdrop of the Iran war.