The extraordinary courage of Alexei Navalny, who survived being poisoned with a nerve agent and then returned to Russia despite near-certain arrest after, has found an echo in the boldness of ordinary Russians. Tens of thousands braved beatings, arrests, temperatures down to minus 50C and potential jail terms to show support for him in protests at the weekend. The participants, like Mr Navalny, threw down a challenge to the Kremlin. They also presented one to the west: to find effective ways to retaliate against the prison term that may now await the opposition activist, and to support democracy in Russia.

What was striking about the weekend protests was less their size than their spread. The estimated 40,000 in Moscow fell short of the six-figure demonstrations over poll-rigging in the winter of 2011-12. But rallies were reported in 110 towns and cities across Russia. Their slogans suggested the protests were fuelled by the nearly two-hour video Mr Navalny’s team released last week — again showing uncommon audacity — describing a lavish $1.3bn palace allegedly built for President Vladimir Putin. In a week, the video has been viewed 87m times.

The protests’ geographical range suggests the middle-class resentment that simmered in Moscow and St Petersburg nine years ago — but was partly “bought off” by investment in both cities’ amenities — is increasingly matched by provincial discontent. The linking of those two strands of dissatisfaction has rattled the Kremlin. State TV, which habitually ignores Mr Navalny, was full of propaganda on Sunday denouncing him as a western agent. Unusually, first Mr Putin’s spokesman, then the president himself responded to the “palace” claims, insisting the building had nothing to do with him.

The detention of Mr Navalny was a blunder that has intensified the Kremlin’s dilemma. If a court next month converts a three-and-a-half-year suspended sentence against the activist on bogus corruption charges into a custodial term, for violating parole terms, he will become even more of a martyr-figure. Yet releasing him would look like a cave-in, leaving Mr Navalny a victor.

The former path appears more likely. The Kremlin would then attempt to contain what may become weekly protests, as neighbouring Belarus has done, in the hope they peter out.

Much will depend on western countries holding Russia to account for Mr Navalny’s imprisonment, and for how it treats his supporters. As much as with China, it is vital for Joe Biden’s US administration to forge a common approach with its allies. China represents, no doubt, the greater long-term challenge to the western-led order. But Russia is the bigger short-term threat.

Moscow under Mr Putin has already annexed the territory of a neighbour, setting a dangerous precedent for the likes of Beijing. It has assassinated opponents abroad, sought to interfere in western elections and conducted the largest cyber attack in memory on US targets. Its ruling elite hides its corruption less well than China’s, is more nervous of its position given its poor economic record over the past decade, and has fewer institutional constraints.

EU foreign ministers said on Monday the bloc would refrain from imposing sanctions on more Russian individuals if the Kremlin released Mr Navalny. That imposes at least some pressure, while allowing time to craft a joint response with Washington. Mr Biden’s first priority must, of course, be to bolster US democracy after the assault on the Capitol. But it would be a disservice to the grit of Mr Navalny and his supporters if he neglected, meanwhile, the cause of freedom of political choice elsewhere.