The UK government on Monday joined international calls for Russia to release opposition politician Alexei Navalny, who was detained on Sunday. Navalny, a prominent critic of Russian President Vladimir Putin, was detained on arrival at a Moscow airport after he flew home to Russia from Germany for the first time since he was poisoned last summer. Navalny could be jailed for three-and-a-half years for allegedly flouting the terms of a suspended prison sentence. “It is appalling that Alexei Navalny, the victim of a despicable crime, has been detained by Russian authorities. He must be immediately released,” UK Foreign Secretary Dominic Raab said in a statement. “Rather than persecuting Mr. Navalny, Russia should explain how a chemical weapon came to be used on Russian soil.” The United States and the European Union have already demanded Navalny’s release. The U.S. Department of State said it “strongly condemns” Russia’s decision to arrest Navalny and demanded his …