Alexei Navalny, Putin's arch-rival and critic, has been discharged from hospital in Germany after recovering from a failed Novichok poisoning.
Doctors at Charite hospital in Berlin say the politician's health 'has improved to such an extent that acute medical care could be ended' after 32 days in their care.
Medics said they 'consider a full recovery possible' given Navalny's current condition, but cautioned that long-term effects of the poison may take a while to become apparent.
Navalny has vowed - via his spokeswoman - to return to Russia to continue his opposition to Putin, though exactly when this will happen is unclear.
Just hours before the news broke, Navalny uploaded a photo of himself in hospital to Instagram, revealing several prominent scars on his neck.
One, at the base of his windpipe, appeared similar to the tracheotomy scar seen on Yulia Skripal - another vicitim of Novichok - as she appeared in public for the first time after being poisoned.
A tracheotomy is a small incision that is used to insert a breathing tube into a patient's lungs when they have lost the ability to breathe for themselves.
Alongside the photo, Navalny posted a message mocking Putin and his suggestion - made in a phone call with Emmanuel Macron - that Navalny could have swallowed the Novichok himself.
'Putin told his French counterpart: "Navalny might have swallowed this poison himself." A good theory. I believe it deserves a most thorough examination.
'I brewed Novichok in the kitchen. Sipped it quietly from a flask while on board the plane. Slipped into a coma.
'Before that, I agreed with my wife, friends and colleagues that if the Health Ministry insisted on me being taken for treatment to Germany, they should not agree to it under any circumstances.
'The final aim of my devious plan was to die in an Omsk hospital and end up in an Omsk mortuary. But Putin has outsmarted me.
'He is nobody's fool. As a result, I, like a fool, spent 18 days in a coma but failed to achieve what I wanted. The provocation has failed.'
The news that Navalny has been released comes five days after he last shared an update on his condition, which showed he could stand and walk.
Pictured standing on a hospital stairwell, the 44-year-old revealed that he had initially been unable to read or write after waking from an 18-day coma that he fell into after being poisoned on a plane in Russia on August 20.
'Until quite recently,' he wrote, 'I did not recognise people and did not understand how to talk.'
It is not clear where Navalny will stay until his eventual return to Russia.
The Kremlin continues to deny involvement in the poison plot, and has requested evidence from Germany to support its conclusion of Novichok poisoning.
Russia has also asked to send agents to interview Navalny, despite NATO warnings that the state 'will try again' to kill him.
NATO chief insist Russia was behind the poisoning, saying there is 'no other explanation', while France and Sweden have also concluded that Novichok - a Russian-made nerve agent - was used in the attack.
It was initially suggested by Navalny's friends that he was poisoned with a cup of tea that he drank at Tomsk airport shortly before boarding the flight where he fell ill.
But his political allies now believe the agent was slipped into a water bottle he drank from at a hotel.
After Navalny fell ill, the aircraft made an emergency landing in Omsk and he was initially taken to hospital in the Siberian city.
The following weekend he was airlifted to Berlin, where doctors at the Charite hospital treated him with the antidote atropine and kept him in a medically induced coma.
On September 2, the German government announced that a military lab had found evidence of Novichok, the Soviet-era nerve agent used to target Sergei Skripal in Salisbury in 2018.
Germany said there was 'unequivocal evidence' of Novichok which has since been independently confirmed by labs in Sweden and France.
Navalny's allies have pointed the finger at Vladimir Putin, saying that only the Russian government could use a military-grade nerve agent such as Novichok.
Western leaders have piled pressure on Russia to explain how Navalny was poisoned, but the Kremlin has denied involvement and played down Germany's findings.
Despite international calls for Russia to carry out a transparent investigation or risk sanctions, it has not opened a criminal probe.
'There are very serious questions now that only the Russian government can answer, and must answer,' Angela Merkel said earlier this month, describing what happened to Navalny as 'the attempted murder by poisoning of one of Russia's leading opposition figures.'
While Berlin stopped short of accusing Russia directly, Navalny's aide Ivan Zhdanov said Novichok 'can only be used by the state' - suggesting that the GRU or FSB intelligence agencies were responsible.
Kremlin spokesman Dmitry Peskov said today that everyone would welcome Navalny's recovery, adding that he was free to return to Russia.
'Any citizen of the Russian Federation is free to leave Russia and return to Russia. If a citizen of the Russian Federation recovers his health, then of course everyone will be happy about that,' he said.
Peskov said the Kremlin was open to clearing up what happened to Navalny, but needed access to information on his case from Germany.
Moscow did not understand why Russia was not being given the same access as French and Swedish laboratories, Peskov said.
A spokesman for Germany's foreign ministry previously countered the Russian line by saying that Russian medics had access to Navalny immediately after he fell ill.
Samples taken from Navalny have also been sent to the Organisation for the Prevention of Chemical Weapons (OPCW) in The Hague for additional tests.
The head of Russia's foreign intelligence service claimed today that Navalny showed no signs of poisoning before he was flown to Berlin for treatment.
'It is a fact that the moment Alexei Navalny left Russian territory there were no toxins in his system,' Sergei Naryshkin said.
'Therefore, we have many questions to the German side,' he told reporters.
Hospital medics said in their sixth official update on Monday that Navalny's condition 'continues to improve'.
'The patient has been successfully removed from mechanical ventilation. He is currently undergoing mobilisation and is able to leave his bed for short periods of time,' the statement said.
'The decision to make details of Mr Navalny's condition public was made in consultation with the patient and his wife.'
Despite his recovery, doctors have said they cannot rule out long-term health issues associated with the poisoning.
The EU's diplomatic chief Josep Borrell today urged Russia to carry out a 'full and transparent procedure' to investigate what happened to Navalny.
Russian Foreign Minister Sergey Lavrov has accused the West of using the incident as a pretext to introduce new sanctions against Moscow.
The apparent assassination attempt has fuelled calls to scrap the Nord Stream 2 pipeline, a Kremlin flagship project to bring more Russian gas directly to Germany under the Baltic Sea.
Navalny has been a thorn in the Kremlin's side for more than a decade, exposing what he says is high-level corruption and mobilising protests.
He has been repeatedly detained for organising public meetings, sued over corruption investigations and barred from running in the 2018 presidential election.
The 44-year-old has also served several stints in jail in recent years for organising anti-Kremlin protests.
The European Court of Human Rights has ruled that Russia's arrests and detention of Navalny in 2012 and 2014 were politically motivated.
French leader Emmanuel Macron's office said he had expressed 'deep concern over the criminal act' in a call with Putin on Monday.
The Kremlin said Putin 'underlined the impropriety of unfounded accusations against the Russian side' and reiterated Russia's demand for Germany to hand over samples.
This article has been adapted from its original source.
© Associated Newspapers Ltd.