However, imagine if Russia sent 5k troops to Cuba. How would US react?
Everyone will always move their troops in response to movement of everyone else’s. There is tension and diplomacy.
Of course, 2022 has no comparison with 1982 technologically, but...
(Also, USSR was "stuck" funding a lot of unprofitable agents and countries abroad, while Russia's main expenditure geopolitically, other than influencing Germany/France/EU, is Syria.)