Pompeo says Russia's behind cyber attack on US. Is it time to respond to this act of war?

Russia Is now engaged in a massive cyber attack of the US federal government and many major private sector businesses. What method should the people of the United States choose to respond to this act of war committed by the Russians?

 I personally think that right now would be a great time to demonstrate to the Russians that the US has the ability to initiate a nuclear attack, and thwart any kind of nuclear attack Russia can try to use in response because of our new missile defense system. 

Maybe you think a nuclear strike is too harsh, so instead you would prefer a more subtle approach, like an EMP attack on a major Russian city. 

Perhaps you are the diplomatic kind who would prefer to have discussions with the Russians on how to settle the dispute civilly (blech) and offer concessions and come to an understanding.

Maybe you think the Russians aren't actually doing anything wrong and should be let alone to conduct their cyberspy mission unabated. That's technically not a response at all, but it does require purposeful decision making to do so none the less. We cannot claim ignorance to the fact that the Russians are indeed committing an act of war on the US as you are reading this, so doing nothing would require at least the decision to do so.   

These are a few of the responses we as a nation could employ. Your thoughts?