Act of war?

Item:

The U.S. government on Friday formally accused Russia of a campaign of cyber attacks against Democratic Party organizations during the campaign for the Nov. 8 presidential election.
U.S. officials have said in the past few months that they believe cyber attacks were orchestrated by hackers backed by the Russian government, possibly to disrupt the election in which Democratic Party candidate Hillary Clinton faces Republican Party candidate Donald Trump. Russia has dismissed allegations it was involved in cyber attacks on the organizations.

Story.

The question is, how do you retaliate - make Russia have a real election?