Protests near the White House on Sunday. (Evelyn Hockstein/For The Washington Post)

“WHERE ARE the protesters?” asked several accounts on Twitter early Monday morning, after most Washingtonians had gone to bed and the Web-waves had quieted. Using the hashtag #DCblackout, they claimed that communications downtown had been blocked to cover up police violence. Then came a series of suspicious missives in identical language declaring that all was well — spurring more concern among observers that something fishy really was afoot.

The entire thing was a ploy, carried out through fraudulent accounts and designed, it appears, to instill panic.

The #DCblackout scare is only one example of the disinformation flourishing amid the week’s anguish and unrest. The favorite tactic of Internet meddlers has been to exploit existing rifts in our society rather than to break open new ones on their own, and this crisis in particular may be ripe for infiltration. The largest Russian troll farm on Facebook leading up to the 2016 election had a go-to topic for sowing discord and division: Black Lives Matter. The Internet Research Agency even attempted to recruit the family members of African Americans killed by the police. America’s endemic racism is an Achilles’ heel.

The threat of mass movements being co-opted by provocateurs both foreign and domestic is serious because it can allow bad actors to contort a conversation to serve their own ends. But it’s also serious because, if malign influence ever is discovered, observers might dismiss even authentic activism as merely the concoction of opportunistic agitators. The temptation to blame so-called outsiders is already proving hard to resist, for example, for President Trump and Attorney General William P. Barr — who declared without evidence this weekend that disorder is “planned, organized and driven by anarchic . . . and far-left extremist groups.”

This tension puts truth-seekers in a tough spot. It’s crucial to root out lies and distortions, and when possible to understand their provenance. Yet it’s also essential to avoid reflexive distrust of what we see and read, as that’s exactly what adversaries want. And it’s essential to avoid distracting from what’s at the heart of the movement that those adversaries aim to penetrate. The best answer is to adopt an admittedly tired adage, ironically popularized from a Russian proverb: Trust, but verify.

How, though? Much of the onus is on platforms to scale up efforts to track viral hoaxes as they unfold, either on their own or in partnership with the journalists and academics already on the job. These platforms should apply fact-checking labels with full context to anything debunked, as well as alert those who have interacted with such content. And they could help everyday users to do fact-checking of their own, too, by verifying the legitimate accounts of organizers and groups, by highlighting accounts that were recently created, by including a history of an account’s names and handles if they weren’t.

Perhaps things would be simpler if discontent in this country could be blamed only on chaos-hungry meddlers. In reality, the role purveyors of disinformation play makes the picture even more complicated. But that’s only a reason to look at it more closely.