Robert McMillan and Kevin Poulsen report: A Moscow entrepreneur was detained during a vacation abroad this month and is now facing extradition to the U.S. on charges that he helped a notorious Russian ransomware group launder payments. The case marks the first arrest in connection with the Ryuk ransomware group, which gained notoriety with a string of attacks last year targeting U.S. hospitals already strained by the Covid-19 pandemic. Denis Dubnikov, a Russian citizen, was expelled from Mexico and placed on a plane to Amsterdam, where Dutch police arrested him on Nov. 2 on a U.S. charge of conspiracy to commit money laundering, according to his lawyer Arkady Bukh. Read more on WSJ.