Russian opposition leader and Putin critic Alexei Navalny has come out of a medically induced coma and is responsive at Charité Hospital in Berlin, according to Reuters. Charité Hospital said in a statement that Navalny “is being weaned off mechanical ventilation” and “is responding to verbal stimuli,” but that “it remains too early to gauge the potential long-term effects of his severe poisoning.”

Navalny, a vocal critic of Russian president Vladimir Putin, became severely ill due to a suspected poisoning that caused him to collapse on a flight from the Siberian city of Tomsk to Moscow on August 20^th. Navalny’s spokesperson, Kira Yarmysh, said in a tweet that she believes he was poisoned from a cup of tea he drank at an airport café earlier that day. Navalny was initially being treated at a hospital in Omsk, which said it found no evidence that poisoning had taken place and instead diagnosed Navalny with a metabolic disease possibly caused by low blood sugar. On August 22^nd, after intense pressure from his family and supporters, Navalny was transported to Charité Hospital in Berlin, where he was put into a medically induced coma.

On September 2^nd, German chancellor Angela Merkel confirmed that the Berlin hospital had found that Navalny had been poisoned with the Russian nerve agent known as Novichok. This is the same nerve agent United Kingdom officials detected in the 2018 poisoning of former Russian double agent Sergei Skripal and his daughter in Salisbury, England. Merkel said that testing carried out by a special military laboratory showed “unequivocal” proof that Novichok was used on Navalny, and that he was a “victim” of a crime that was intended to “silence” him. “This raises very difficult questions that only the Russian government can answer, and has to answer,” Merkel said.

Many of Navalny’s supporters in Russia believe that the poisoning demonstrates Kremlin involvement. Leonid Volkov, Navalny’s chief of staff, tweeted that “choosing Novichok to poison Navalny in 2020 is basically the same thing as leaving an autograph at the scene of the crime,” and attached an image of Putin’s signature to the tweet. Ivan Zhdanov, one of Navalny’s aides, similarly tweeted that “only a government can do this.” Ben Noble, a lecturer in Russian politics at University College London, told TIME that the use of Novichok to poison Navalny suggests one of three scenarios: One, that Putin ordered Russia’s secret service or military intelligence to poison Navalny. Two, that Putin gave his implicit approval for another actor to carry out the poisoning of Navalny. Or three, the state was not involved at all and Putin has lost control over how chemical weapons are used in his country. The Kremlin has continually denied any involvement in the poisoning of Navalny, according to CNN.

Navalny has long been a prominent face of Russian opposition to Putin and has campaigned on an anti-corruption platform. According to BBC, Navalny has called Putin’s party a place of “crooks and thieves,” accused Putin’s party of “sucking the blood out of Russia,” and vowed to destroy the “feudal state” being built. He has also led nationwide protests against the authorities.

If it is true that Putin and the Kremlin poisoned Navalny in order to eliminate one of their most vocal opponents, this action should be internationally condemned as an authoritarian and undemocratic move. Chancellor Merkel has promised an investigation into Navalny’s poisoning by the E.U. and N.A.T.O., and British prime minister Boris Johnson has denounced the poisoning as “outrageous.” The E.U. has urged Russia to conduct a “transparent” investigation into the poisoning. Perhaps the U.N. should also launch their own independent investigation into Navalny’s circumstances.

If the Russian government had any part in poisoning Navalny, it was in an attempt to silence the face of the opposition. This would mark an attempt to silence their own people, who deserve to have their voice heard. The people of Russia should be able to voice their dissent without fearing that they may be poisoned or suppressed in any way. The international community must step up, investigate Navalny’s poisoning, and hold the perpetrator, whoever that may be, accountable for their crimes.