UN nuclear monitor warns of consequences if major powers resume testing

The head of the organisation responsible for overseeing the global treaty banning nuclear testing warned that any resumption of tests by major powers could trigger a wider and potentially uncontrollable chain reaction.

Robert Floyd, executive secretary of the Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO), said that if the United States, Russia or any other country proceeds with nuclear testing, others are likely to follow.

“That is a spiral that we do not want to see start, because it may never be able to be stopped,” Floyd told United Nations correspondents on Wednesday.

His warning comes amid renewed tensions over nuclear policy. Late last year, both the United States and Russia — which possess the world’s largest nuclear arsenals — signalled the possibility of resuming nuclear testing, raising global concerns.

Floyd noted that when the Comprehensive Nuclear-Test-Ban Treaty (CTBT) opened for signatures 30 years ago, more than 2,000 nuclear tests had already been conducted worldwide. Since then, however, fewer than a dozen tests have taken place, including six carried out by North Korea.

The remarks were made as the United Nations this week began a review of a separate treaty aimed at preventing the spread of nuclear weapons. The review is taking place against the backdrop of the Iran war, which President Donald Trump has said was necessary to prevent Tehran from acquiring a nuclear weapon.

Although the CTBT was adopted in 1996, it has not entered into force because it requires ratification by 44 specific countries, nine of which have yet to do so.

Among those, 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 had both signed and ratified the agreement but revoked its ratification in 2023.

Floyd stressed the importance of coordinated action by major powers, saying a pathway should be found for China, Russia and the United States to ratify the treaty together, which he said would “certainly be a powerful step forward.”

While China and Russia have stated that they continue to observe a moratorium on nuclear testing, the US State Department has, since 2019, publicly raised concerns about activities in both countries. At the end of last year, President Trump accused Russia and China of conducting tests and said he had instructed the Defence Department to begin testing nuclear weapons “on an equal basis.”

In response, Russian Deputy Foreign Minister Sergei Ryabkov said Moscow would only resume nuclear testing if Washington acted first.

Floyd said he recently travelled to Moscow, where he discussed the issue with Russian Foreign Minister Sergey Lavrov, emphasising “that it is not in any state’s interest to see an unconstrained return to testing.” He added that he has also held meetings with officials from the US State Department and would welcome the opportunity to meet Secretary of State Marco Rubio.

Highlighting the capabilities of the treaty’s verification mechanisms, Floyd said the CTBT’s international monitoring system is capable of detecting even relatively small nuclear explosions anywhere in the world. Any country attempting to develop a nuclear weapon would need to test it, and “if they did it will be known to all,” he said.

By Tamilla Hasanova