Should the US have nuked Russia in 1946?

No. Because THEN The Soviet Union would've become OUR Responsibility. And we would have Bankrupted OurSELVES- into the Process of rehabilitating that Country's 200 MILLION People ( And China would the World's only Superpower now). There are NO "Quick Wars." Only very Expensive Ones- with LOTS of Unintended Consequences... :(