The United States believes Russia may be conducting low-level nuclear tests, a U.S. intelligence official on Wednesday, while the head of a body monitoring a global nuclear treaty said there was no sign of such violations by Moscow. Negotiated in the 1990s, the Comprehensive Nuclear Test Ban Treaty (CTBT) enjoys wide global support but must be ratified by eight more nuclear technology states, among them Israel, Iran, Egypt and the United States to come into force.

Russia ratified it in 2000. However, the head of the U.S. Defense Intelligence Agency (DIA) said, "The United States believes that Russia probably is not adhering to its nuclear testing moratorium in a manner consistent with the ‘zero-yield’ standard." At an arms control forum at the Hudson Institute, DIA head Lieutenant General Robert P. Ashley said, "We believe they have the capability in the way they are set up" to conduct low-level nuclear tests that exceed the zero yield limit set in the CTBT. There was no immediate response from the Russian government, but the head of the Russian State Duma Defense Committee, Vladimir Shamanov, told the Interfax news agency that Ashley "could not have made a more irresponsible statement." "Nuclear tests cannot be carried out secretly," it quoted him as saying.