Nobody wins in a nuclear exchange, both countries will be obliterated (unless it is limited use of nukes, like maybe 20 total) and the whole world will feel it, an exchange involving the US will for sure end the world, unless things change alot in the next 20 years, because we will not launch a nuke unless attacked first, we have the most powerful Army in the world, with our carriers we could use conventional weapons anywhere in the world to get our point across, we don't need to use nukes, unlike Russian, China, Korea, India, or Pakistan, we have the offensive capabilities to hit any point in the world with conventional weapons in less than 48 hours.