Can they?
Russia has not conducted a nuclear weapons test since 1990 when they were the Soviet Union. Much has changed since then.
There has been a 2nd 'freeing of the serfs'. Nuclear Weapon and missile techs don't have to settle for a shabby apartment and access to the state store and have moved on.
For example, a thermonuclear weapon requires tritium, a rare isotope of hydrogen that is extremely rare in nature and requires manufacture in a reactor to boost the fission stage.
Tritium has a half life of 12 years and decays to lithium which absorbs electrons and causes your nuke to fizzle. So every few years you have to replace your tritium.
Do the Russians still have techs they can trust to do that? For thousands of weapons?
Or have they been bluffing for years now?
Trump and Mattis have known what they were doing everytime before...
Tritium decays to helium-3. Tritium can be PRODUCED FROM lithium-6 by neutron activation.
Do the Russians still have techs they can trust to do that? For thousands of weapons?
I certainly wouldn't bet against it...