With the release of thousands of Russian Facebook ads, the debate is over: As the intelligence community and members of Congress of both parties acknowledge, hostile foreign powers led by Russia definitely interfered in American politics by peddling propaganda to influence our 2016 elections. It was a harbinger of 21st century, digital-age information and psychological warfare. The question now is: How do we fight back?

Propaganda is an age-old wartime tactic to win or defeat hearts and minds. The word itself conjures images of Joseph Goebbels and the Nazi Ministry of Propaganda, airdropped leaflets, and Soviet posters extolling communism. Or more murderously, Rwanda’s government-sponsored hate radio that incited the 1994 genocide against the ethnic Tutsi.

During World War II, Allied troops in the South Pacific were targeted by “Toyko Rose,” the name given several female radio personalities broadcasting Japanese propaganda meant to mislead or demoralize our forces. “She” would tease the (mostly) men that their lonely beloved ones back home were dating others. It didn’t work. But as the late radio broadcast historian Jerome Berg noted, that was because the vast majority knew it was propaganda and considered the source.

That is not so easy in today’s post-truth, fake-news internet age, when the public is overwhelmed by information and disinformation and does not have the tools to know what is true. We no longer accept Founder John Adams’ dictum that, “Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence.” Today, as many note, we are guided more by subjective belief than objective fact.

Foreign propagandists are exploiting internet and social media for cheap, easy, instant access to millions of unsuspecting people, anonymously and without accountability. The Cold War secret agents are now computer agents — human “trolls” and automated “bots” — that infiltrate trusted news feeds, mine user data, and flood us with propaganda-motivated comments, memes and GIFs that seem real to believers.