What was the greatest, most devastating attack on American soil that didn’t claim a single life?

PBS’ “Frontline” makes a decisive case for Russian President Vladimir Putin’s hacking of the 2016 presidential election.

In part one of “Putin’s Revenge” (Wednesday at 10 p.m.; part two airs Nov. 1), the Boston Emmy Award-winning documentary series examines Putin’s rise to power and the roots of his decadeslong grudge against America and, specifically, Hillary Clinton.

The former KGB operative came to believe that the United States was devoted to regime change across the world and would unseat him in a hot minute if given the chance. Former Secretary of State Clinton drew his festering ire in 2011 for allegedly providing comfort and aid to Russian dissidents, a slight he never forgot.

Part two of the report argues that with an army of hackers at his command, Putin viewed the 2016 presidential election as a chance to exact some payback and test out a new form of warfare — cyberwarfare, on several fronts.

In addition to fake ads on social media and possibly millions of fake social media accounts pumping out disinformation, his keyboard commandos hacked the Democratic National Committee, which, given the digital security there, seemed about as simple as strolling through an open door.

The FBI knew the DNC had been compromised but couldn’t get anyone there to take its phone calls seriously. No one at the bureau could be bothered to walk the 12 minutes (including time to stop at Starbucks, we are told) to warn the DNC in person.

Clinton campaign chairman John Podesta’s emails proved to be the Wikileaks scourge that kept on giving all election season long.

In Donald Trump, Putin found a presidential candidate he could admire — one who didn’t view the hacking as foreign meddling but who exploited and welcomed the content on the trail.

“Wikileaks! I love Wiki­leaks,” Trump told a crowd at a campaign stop.

Despite CIA confirmation of the Russian hacking, President Obama and his administration are depicted as hopelessly dithering on how to inform the American people without further polarizing the election.

And yet as footage inside Russia shows, Russians were just as surprised as many Americans were when Trump won the election.

The Atlantic’s Julia Ioffe comments, “They just thought they would bloody Clinton’s nose. They didn’t expect to break her neck.”

“Frontline’s” cavalcade of experts, including top diplomats, intelligence operatives, politicians and historians, goes beyond the usual talking heads. The impact of the investigation might be greater aired as a single special in one night. The second part (admittedly, a rough cut) was a bit repetitive in places.

At the close of the second hour, former Director of National Intelligence James Clapper warns, “The Russians aren’t going to stop. Their experience in our 2016 election is going to embolden them to interfere in the future, maybe more aggressively.”

We have an enemy determined to tear apart America.

What are we going to do about it?