Russia interfering with a US election is an act of war and should be treated as such. They also tried to influence the French election with hacking.
The US should expel all Russian diplomats and freeze all assets of Russian companies doing business with the US.
Of course, Trump is hiding his tax returns likely because he has financial dealings with Russia which is why he is so dangerous in a position to make these decisions. He won't do anything to the Russians. And the Republicans in Congress who have given up defending America against it's enemies will be complicit with Trump in alloweing Russia to continue to play the US as it's bitch.
Just for a moment consider what the Republican's favorite fuck-buddy Raygun would think of this. Even that criminal would be vomiting in his grave.