Anyone in Europe and Britain worried about the state of US democracy should take time to watch the videos of this week’s congressional hearings over Russian online meddling in the 2016 presidential election. If the words “checks and balances” mean anything, this surely is it.

My favourite moment is when senator Dianne Feinstein leans into the microphone and says sternly to the Facebook, Twitter and Google representatives (whose evasive answers have exasperated her): “You don’t get it! This is a very big deal. What we’re talking about is cataclysmic. It is cyber warfare. A major foreign power with sophistication and ability got involved in our presidential election.”

We don’t yet know the full picture. In particular, we don’t know if Russian-promoted bots, trolls and online ads had an impact that in any way altered the outcome of the US election. At this stage, to claim they did may be crediting Vladimir Putin with more power than he actually wields. What emerged from the hearings is that Russia’s likeliest goal was to sow discord and confusion among citizens of the world’s most powerful democracy.

Russia’s attempts to undermine western democracies may be only the tip of the iceberg. Think China

Still, it would be wrong to think this affects America alone. Europe and Britain are directly concerned by what the US investigations will uncover. Atlanticism and its security dimensions are much debated these days. (Questions also lurk in the background over the national act of self-mutilation that is Brexit.) But the transatlantic relationship has a new dimension to explore: the online world. Feinstein hinted at this when she said: “The US is the first country to bring attention” to the “responsibility” of tech giants in making sure social media isn’t turned into an instrument of authoritarianism rather than a platform for citizens’ freedom. “Other countries will follow,” she said.

The ripple effects of the US investigations into Russian meddling will be felt in Europe also.

Russian interference in Europe’s politics and its information space is not new, of course. Its roots lie in old KGB disinformation methods, now actively combined with new technologies. In Britain, the question has taken on an important new twist, with growing calls for parliamentary scrutiny of the financing of the pro-Brexit campaign, whose social media dimension mattered greatly. If the “special relationship” still has meaning, surely it must now include a joint effort to get to the bottom of how Russian social media manipulation in the US resonated with what happened in the UK referendum.

The ramifications of this debate are huge. The US and the UK, the two countries that laid the foundations of the post-1945 global liberal order, may have had their political integrity compromised by hostile foreign meddling in a way that helped produce Trump and Brexit. If that turns out to be true, then we are looking at an entirely new world – one whose complexities we may only be starting to fathom. Orwell’s Nineteen Eighty-Four, written 70 years ago, contained not just “newspeak”, “facecrime” and surveillance screens. It also described a geopolitical vision in which “Oceania” (including the Americas and Britain), “Eurasia” and “Eastasia” were all in the grip of totalitarian nightmares, with control over minds even more important than control over bodies.

Literary analogies shouldn’t be abused, but the US probe surely has deep significance for other parts of the world too – and European democracies need to pay close attention. Make no mistake, this isn’t just about Trump and whether his campaign colluded with the Kremlin. It is about how the large, ungoverned areas of cyberspace are the new arena where authoritarian powers and democracies will increasingly be waging a battle – one that the latter are insufficiently prepared for. Likewise, Russia’s attempts to undermine western democracies from within may be only the tip of an iceberg that is heading towards us. Think China. At a recent thinktank conference in Brussels, I was struck by how some European business people were head over heels about China’s “One Belt One Road” project to Europe. One participant gushed that the Chinese firms were “so good” at using new technologies and data – no matter that the regime has utilised its skill at data mining for the purposes of crowd control and suppressing dissent. Recent revelations about how China imposed online censorship on entities such as Cambridge University Press and the Springer publishing group should be ringing more alarm bells. China has incomparably larger resources than Russia, whose economy is the size of Italy’s.

In the US hearings, another senator, Mark Warner, pointed out that Russian cyber strategies in the US “will no doubt be duplicated by other powers who are enemies of democracy. This is not just an American problem. Other foreign operatives have read this playbook.”

Interestingly, the Facebook representative was then asked whether the platform would suppress specific content in a geographical area to abide by local laws including, for example, taking down a Chinese dissident’s postings. He partly deflected the question by answering that Facebook did so already in Germany, where legislation bans Holocaust denial. That moment, if anything, brought a small glimpse into the many complex aspects of a debate that will define much about whether democratic principles can be upheld in a technologically interconnected world.

How Russia used social media to divide Americans Read more

Europe has no tech giants of its own. In fact, it’s only starting to build its single digital market. So the US probe into how Silicon Valley platforms are used as Trojan horses by foreign autocracies serves as a groundbreaking exercise. Marietje Schaake, a Dutch MEP, notes that “the digital revolution has led to a redistribution of power, but not to a redistribution of accountability and oversight”. She adds: “The global tech companies are the new sovereigns, but are designed to maximise profit – not democracy.” She’s calling for “digital democratic conventions” that might help set up rules.

None of this is simple. But if there’s a lesson to be drawn from the US hearings, it is that the law of the jungle rules in social media. That has massive implications. With Europe’s populist wave still pounding the continent, it is high time for us, too, to find solutions. After all, if Russian troll farms can impersonate Black Lives Matter activists and white supremacists in the US, what can they be up to in Europe? And who’s looking into this?

• Natalie Nougayrède is a Guardian columnist