The scary thing about Russian nuclear arms is the shift from a deterrence to a strike first policy. Although, one could estimate that it is a policy meant to temper western responses and encourage diplomatic, rather than military responses (i.e. alarm from the west at a potential nuclear strike that leads to inaction).
Russia's military inventory has been dwarfed by the U.S. and NATO over the years. Not to say Russia doesn't have state-of-the-art stuff - fighters, SAMS, ground equipment, etc. They certainly do. But western investment - for better or worse - has pulled ahead in what used to be a neck-to-neck race. With a few exceptions...
The aforementioned nuclear policy. It's not necessarily a capability, but a position of suitability (i.e. what Russia is willing to do, or at least project in their overt policy). Electronic warfare (I've attached a 2017 ICDS study highlighting Russia's attention to these capabilities)....Russian military leadership understands our C4ISR capabilities and reliance on the EM spectrum (be it the operation of our myriad systems, or command and control and the very ability to "act"). They've prepared to degrade it and operate in that environment. Cyber warfare...honestly, that is one of the biggest issues facing nations in peace or wartime. Be it military or civilian systems and state or non-state actors. If you're not familiar with the breadth of threats, here is a good open source primer of advanced persistent threats and the nations they benefit....https://attack.mitre.org/. Shit is scary and we're just taking notice and measures. Finally, Russia's use of proxy groups..."little green men", Wagner (Vagner) group, whatever name we call them....Russia has expertly wielded them to control territory, enact atrocities, lead separatist forces, and allow for deniability (be it Ukraine, Syria, Africa, etc.).
