He has been repeatedly arrested, nearly blinded in one eye by chemicals thrown in his face, and poisoned with a sinister nerve agent. Alexei Navalny’s announcement this week that he would fly home to Russia on Sunday, despite a dubious new criminal probe launched while he has been recovering in Berlin from the attempt on his life, was nothing if not gutsy. On Thursday, Moscow raised the stakes by signalling the anti-corruption blogger would be detained on arrival pending a court decision on whether to turn a suspended sentence into a jail term. Mr Navalny must now decide whether to go ahead. Either way, Vladimir Putin’s Kremlin has again revealed its real nature — and how much it fears the political activist.

After his extraordinary recovery from novichok poisoning, Mr Navalny faced the same choice as a long line of Kremlin opponents: pursue a marginalised life as an exiled dissident, or continue political activities but risk jail, or worse, in Russia. Prosecutors last month opened a probe into claims that he embezzled Rbs356m ($4.85m) of donations to his anti-corruption group, which could lead to a 10-year sentence.

The prison service meanwhile accused Mr Navalny of failing to register on 29 December as required by a probationary period linked to a 2014 fraud conviction that the European Court of Human Rights has ruled was politically motivated. The service alleged on Thursday that Mr Navalny had failed to appear six times in 2020. A court will decide on January 29 if those violations merit converting the three-and-a-half year suspended sentence the activist received into real jail time.

The choice facing Mr Navalny echoes that of Mikhail Khodorkovsky in 2003. Russia’s then richest man chose to ignore hints that he should flee after falling out with Mr Putin. He ended up spending 10 years behind bars.

Yet the activist’s return would also pose a dilemma for the Russian president. Allowing him to remain at large would appear weak, and enable Mr Navalny to support candidates in Duma elections in September about which the Kremlin is already jittery. Even more than before, the activist is a hate figure for the FSB security service — which Mr Putin once headed — after working with investigative groups on two heavily-viewed YouTube videos documenting the alleged FSB plot to assassinate him. In the second, Mr Navalny appears to dupe an FSB officer into admitting plans to kill him by smearing novichok on his underwear.

Jailing Mr Navalny would appear heavy-handed and cowardly to the outside world, risk western sanctions, and make him a behind-bars rallying figure for the opposition. Analysts have suggested his wife could become Russia’s equivalent to Svetlana Tikhanovskaya, the Belarusian opposition leader. An arrest on Mr Navalny’s return to Moscow would take place in the glare of international media and supporters planning to greet him at the airport.

If the opposition figure calls off his homecoming, few supporters will respect him any less. If Mr Navalny goes ahead and is detained, the west should signal a robust stance towards any prison term. It may be too late to stop the egregious Nord Stream II gas pipeline. But oil groups with big Russian investments such as BP and France’s Total should think hard about their involvement, especially as they already face pressure to shift to a lower-carbon future. Ethical investors should be looking not just at what these companies invest in, but where. Western capitals meanwhile should make clear they will respond with much tougher sanctions than the paltry measures against a few senior Russians that followed his attempted assassination.