With no evidence to support the allegations, US DIA officials are accusing Russia of potentially having the capability of violating the Comprehensive Nuclear Test Ban Treaty. Russia ratified this treaty in 2000, and the US has never done so.
There is a global system that would immediately detect a nuclear test,
which led Russian MP Vladimir Shamanov to mock the US military for
“failing professionalism” as he noted that nuclear tests cannot be
carried out secretly.
The State Department defended the DIA allegation, for which again no
evidence exists, on the grounds that the US believes Russia “routinely”
disregards its international obligations. That a major nuclear state
like Russia could conduct a test is not in question, of course, the
treaty simply forbids them from doing so, which again, they haven’t.
These allegations are potentially dangerous, as the US has in the past
started accusing Russia of a violation, and just kept repeated the claim
until they decide to launch some major diplomatic fight with Russia
over the allegation, on the grounds that they’ve repeated it so long
that everyone in the US just assumes its true.