Editor's Note: (Sharon Burke is a senior adviser to the International Security Program and Resource Security Program at New America. Previously, she served in the Obama administration as assistant secretary of defense for operational energy and in the State Department for the George W. Bush administration. The views expressed in this commentary are solely the author's.)

(CNN) In the Cold War canon of movies that imagined what World War III would look like, there were armed teenagers in the Rockies, submarines in Cape Cod, and plenty of postapocalyptic grit. Regardless of the scenario, however, Americans always fought back.

Now the Russians really are here, infiltrating every corner of the country, with the signal goal of disrupting the American way of life. And enormous numbers of Americans are not only failing to fight back, they are also unwitting collaborators, -- reading, retweeting, sharing and reacting to Russian propaganda and provocations every day.

Sharon Burke

Meanwhile, according to Gallup, US public opinion of Russian leader Vladimir Putin improved between 2015 and 2017. Most of that gain was with registered Republicans, quite a turnaround for the party of Eisenhower, Nixon and Reagan.

Earlier this month, Russian intrusions took a sinister new turn, with the joint FBI-Department of Homeland Security disclosure that the Russians have been hacking US infrastructure, including the electric grid. If you weren't already worried about Russia, you should be now, and it's past time for the United States to define what a "proportionate response" looks like in these new forms of grayscale warfare (not armed conflict, but not peaceful coexistence, either).

Here's why Americans should be worried. According to the FBI and DHS, the Russians have been stealing information and testing attack scenarios on the structure and operations of the US electric grid, including industrial control and Supervisory Control and Data Acquisition systems. Attacking those systems, particularly in a way that does permanent damage, could lead to a prolonged power outage.

Now imagine your life without electricity. No light, no smartphones, no Internet of Things or things of the internet, no banking, and in many cases, no water or fuel, because those systems often rely on pumps and other electrical equipment. Most US military bases depend on civilian grids, too, and backup generators can only take our increasingly electrified force so far.

It is difficult to judge Russian intent, of course, but history is full of wars where civilian infrastructure was a target, and sometimes even a weapon. From the Spartans' ravaging of Athenian crops in ancient Greece to America's "shock and awe" in Iraq, attacking food, water, transportation and communications has long been a way to cut a military off from its supplies, generate political pressure, and destroy the public morale of an enemy.

In the Digital Age, electricity is the ultimate target (and the Pentagon no doubt knows where all Russia's power plants are, too). What's new, however, is the ability to attack this target without firing a shot or crossing a border, which would be an overt act of war. The Russians proved in Ukraine that they can and will shut down electricity from afar in an undeclared war. It's not easy to do, but Russia also will not be the last country to use or gain that capability.

The United States urgently needs to strengthen our defense of the national grid system. This cannot be just the responsibility of the private sector, for a number of reasons. First, there are more than 8,000 power plants in the country, ranging from large, well-connected investor owned utilities to small, rural co-ops with a fraction of the customer base. There are thousands of companies that own or supply equipment in this complicated mix of wires, metal, and minerals. These businesses are generally optimized for reliability, not security, which makes sense, given that weather, human error, and animals damage grid infrastructure and cause power outages in the United States every day. As one industry executive told me: "We're ready for squirrels, not nation states."

Right now, however, the US government does not have a coherent grid security policy: Even the coverage of the recent alert mentioned DHS, the FBI, CYBERCOM, and the Department of Energy. There are other players in the mix, as well, including the Federal Energy Regulatory Commission and the North American Electric Reliability Corporation. It's urgent to clarify roles and missions, clearly designate who will take the lead, and produce coherent, thorough threat assessments. That also means ensuring the grid security agencies have sufficient staffing, technology, funding and leadership support. We can't expect the FBI to keep us safe from attacks on the homeland, for example, if the commander in chief is constantly undermining the institution itself.

Speaking of the President, it is also vital that he direct the National Command Authority (the defense chain of command, including intelligence and military leaders) to give him options for responding to Russian aggression. This is not just about Russia, either; this is about setting the precedent for how the United States will respond when we are attacked in this new gray era.

It's not just up to the President, though. In those Cold War movies, back in the days when Americans fought back, we also stood together and had as much confidence in the power of our ideas and strength of our economy as we did in our force of arms. Maybe those were just works of fiction, but ultimately, the buck still stops with all of us if we're going to keep the country safe in the Digital Age.