Kremlin critic Alexei Navalny was ordered to remain in custody for 30 days during a surprise hearing in Russia on Monday, less than 24 hours after he returned to the country and five months after he was poisoned with the nerve agent Novichok.The opposition leader flew back to Moscow from Germany on Sunday, and was immediately detained by masked officers. He was held overnight a police station in the city of Khimki, on the outskirts of Moscow.Navalny was placed on the country's federal wanted list last month for violating terms of probation related to a 2014 conviction for fraud, which he dismisses as politically motivated.Russia's Federal Penitentiary Service (FSIN) has requested that a court replace his suspended sentence with a prison term. If the request is granted, Navalny will likely be jailed for 3.5 years.On Monday morning, Navalny faced an unexpected hearing scrambled together in a makeshift court inside the police station that was slammed by his supporters as a "circus."The activist's lawyers said they were handed a notice about the proceedings just minutes before it was scheduled to start, and didn't have a chance to review any documents or talk to Navalny.Navalny himself was escorted out of a cell moments later under the impression he would finally be able to meet his defense team, but found himself in the court hearing. In his first appearance since he was detained by border inspectors at Moscow's Sheremetyevo airport last night, Navalny slammed the proceedings as "lawlessness at its highest point" and a "mockery of justice."His spokesperson Kira Yarmysh noted that the only people who appeared to have known in advance about the hearing were a state TV crew and reporters from a pro-Kremlin tabloid, leading Navalny to request that "real journalists" are allowed inside. About 200 journalists and supporters gathered outside the police station where the hearing took place, according to the Mediazona news outlet.In a video posted to his YouTube account following the court decision to keep him in custody, Navalny urged his followers to "not be silent" and take to the streets."What are these crooks sitting in their bunkers are most afraid of? You know this very well. people taking the streets. That is the political factor you can't ignore; that's the most important factor, the essence of politics. So come to the streets, not for me but yourself and your future," Navalny said."I urge you not to be silent, to resist, to take to the streets. No one but ourselves will protect us, and there are so many of us that if we want to achieve something, we will achieve it."The head of Navalny's regional headquarters, Leonid Volkov, announced a nationwide demonstration to demand his release on Saturday.Navalny has been a perennial thorn in Russian President Vladimir Putin's side, raising concerns for his safety in the country.A joint investigation by CNN and the group Bellingcat implicated the Russian Security Service (FSB) in Navalny's August poisoning, piecing together how an elite unit at the agency followed Navalny's team throughout a trip to Siberia, when Navalny fell ill from exposure to military-grade Novichok.The investigation also found that this unit, which included chemical weapons experts, had followed Navalny on more than 30 trips to and from Moscow since 2017. Russia denies involvement in Navalny's poisoning. Putin himself said in December that if Russian security services had wanted to kill Navalny, they "would have finished" the job.Nevertheless, several Western officials and Navalny himself have openly blamed the Kremlin. Governments around the world criticized Navalny's arrest on Sunday and called for him to be released. Secretary of State Mike Pompeo said the "United States strongly condemns Russia's decision to arrest Aleksey" in a statement Sunday. "We note with grave concern that his detention is the latest in a series of attempts to silence Navalny and other opposition figures and independent voices who are critical of Russian authorities."UK Foreign Minister Dominic Raab called Navalny's arrest "appalling" and said the opposition leader had been "the victim of a despicable crime" in a tweet Monday. "Rather than persecuting Mr. Navalny Russia should explain how a chemical weapon came to be used on Russian soil."Russian Foreign Minister Sergey Lavrov deflected the criticism, saying the the West was attempting to "divert attention" from its own problems."We saw yesterday how seized on the news about Navalny's return to the Russian Federation. You can clearly feel the joy with which the carbon-copy comments are incoming," said Lavrov during his annual press conference Monday. "With joy, because it seems to allow Western politicians to think that they will be able to divert attention from the deepest crisis in which the liberal model of development finds itself."Russian officials usually attempt to keep up appearances of an impartial judicial system, but the optics and swiftness in processing Navalny's case Monday shocked his supporters."What is happening with Navalny is worse than a circus. What remote hearing? On what grounds some Khimki cop is trying to keep a person in custody? This is pure hell. Will they shoot him in the end?" Vladimir Voronin, a lawyer with the Anti-Corruption Foundation, said in a tweet.Symbolically, a portrait of Genrikh Yagoda, the head of the Soviet Union's NKVD secret service during the prime years of Joseph Stalin's 1930s purges, loomed over Navalny in the hearing room on Monday, according to footage posted online.