The purpose of these visits by Russian warships to Cuba, IMO, is to rise awareness in the US electorate of what the Cuban Missile Crisis entailed.
IMO on a secondary level these Russian Warships/Nuke Subs Cuban visits are establishing a regular friendly port close to the USA should assistance be needed by the Venezuelan Government. (election pending)
So, IMO , this Ukraine has a global dynamic and the recent visits of Russian Warships/Nuke Subs close to US territorial waters is merely part of that dynamic but most of it is still Economic orchestrated & funded by China.
(source: the Diplomat)
PS : just as the US skewed Ukrainian elections/popular opinion, IMO China is doing ditto in Venezuela right now. That's Geopolitics for ya! nothing to do with non interference by foreign agents in domestic politics !