"Falsehood flies, and the truth comes limping after it," wrote Jonathan Swift more than 300 years ago. What would he have said in the age of Twitter?

A sobering paper published in the winter edition of Strategic Studies Quarterly - the strategy journal of the United States Air Force - explains how propagandists manipulate social media in their cyber wars against the US.

In his paper, Commanding The Trend: Social Media As Information Warfare, Lieutenant-Colonel Jarred Prier examines strategies and tactics used by the Islamic State in Iraq and Syria and the Russian government to seize command of trending topics on Twitter and, to a lesser degree, Facebook.

By hijacking these algorithms, enemy agents and their armies of bots inflame tension and erode trust across American society.

A striking example, which Lt-Col Prier documents in detail, came during the November 2015 protests at the University of Missouri. A dispute over benefits for graduate teaching assistants had escalated into broad allegations of racism on campus.

Spotting the trending hashtag #PrayforMizzou, a Russia-linked Twitter account, @Fanfan1911, tweeted a photo of a bruised African-American youth that was lifted from an unrelated story. "The cops are marching with the KKK!" the tweet declared. "They beat up my little brother! Watch out!"

This untrue message, signed "Jermaine", was retweeted hundreds of times by Russian bots - enough to unleash it as a viral contagion among duped Americans, including Missouri's student body president.

As other accounts in the orbit of @Fanfan1911 added fake details, Jermaine demanded the news media cover the non-existent Klan rampage. Twitter-obsessed reporters ran in search of a story.

Though the facts eventually came limping onto the scene, lasting damage was done. Morale and enrolment sagged at the university. Trust in the media and the police took another hit. The reputation and economy of Missouri absorbed a blow. Not bad for a single shift at the disinformation factory.

Lt-Col Prier follows Jermaine as his display name morphs into FanFan to stoke false rumours of Muslim refugees raping German women in spring 2016. He transforms again into DeplorableLucy to support the Donald Trump campaign.

In each incarnation, the agent employs the same tools: distorted or fabricated narratives, legions of retweeting bots, existing networks of unsuspecting partisans ready to believe the worst, allegations of elite corruption, and the viral engine of trending hashtags.

Director of National Intelligence Daniel Coats reported to Congress this past week that such efforts are designed "to exacerbate social and political fissures in the United States", "to create wedges that reduce trust and confidence in democratic processes", and "to encourage anti-US political views". It is working.

That's why this challenge is critical to our national security. We cannot tackle either threats or competition from China, North Korea, Russia or violent Islamist extremists without a common sense of purpose at home and supportive allies abroad.

Lt-Col Prier wraps up his paper by calling on social media firms, political leaders and journalists to come to the aid of the country.

Twitter, he notes, faces a particular quandary because bot networks and the trending-topic feature - two key weapons in the enemy's arsenal - are both integral to the company's business model.

Advertisers love Twitter bots, while the trending algorithm lends an air of urgency and authority that the platform would otherwise lack.

On the other hand, I see no good reason journalists cannot go straight to work curbing our "over-reliance on social media for breaking news", as Lt-Col Prier puts it.

Reporters should treat every tweet with scepticism and demand real-world confirmation of tweeted "news" before sharing it.

What we need from politicians is sufficient leadership to raise the issue of cyber defence above the muck of partisan advantage.

Sparring over the Trump-Russia investigation is of passing importance compared with the survival of open societies.

It is up to every woman, man and child to show that self-government can survive the digital revolution; to educate ourselves in the use and abuse of personal tools of mass communication; and to employ these tools without stoking social division.

WASHINGTON POST