There are a multitude of factors that would dictate what would happen if these two superpowers went to war:
1. The Initiation of Hostilities
If Russia were to initiate hostilities, it would likely start with missile attacks that would aim to destroy U.S. bases within Europe throughout Asia in order to cripple NATO’s command structure and eliminate U.S. options for reinforcement.
The United States would likely respond with:
Carrier strike groups in the Hind Ocean and Atlantic Ocean.
Stealth airstrikes deep within Russian territory.
Cyberattacks that would blind Russian radar, communications, and satellites.
2. The Regions of Conflict
Europe would likely be center stage for a war. Eastern Europe and the Baltics would be included within this main battleground.
The Black Sea and Arctic would harness Russian defensive strength.
The Pacific would allow U.S. naval capacity to dominate Russia’s forces.
3. The Cyber & Space War
Expect both American and Russian attacks directed towards infrastructure (locational changes such as electricity, GPS, internet, and possibly even satellites). Each of these countries have advanced cyber-warfare capabilities and will presumably attack civilian systems as well as military systems.
4. The Nuclear Question
If either side perceives its destruction, the system can easily escalate to nuclear war. Both countries have thousands of nuclear warheads, that is enough for each side to destroy the other and lead to the end of the world.
Conclusion: There is no winner
Russia may have a quantitative edge in missile technology, and the U.S. may have an edge in maritime and global reach, but a war between them will still destroy both countries.
If conventional: It would be a long, widespread war with global consequences.
If nuclear: It would end civilization.
Ultimately, both sides are aware of this – at least that is why a war remains unlikely for the time being- the balance of power and fear of mutual destruction remains, albeit tenuously.