The Army has stopped paying wages and allowances to a U.S. soldier sentenced last month to nearly four years in a Russian penal colony and may prosecute him if he returns to the United States, U.S. officials said. Gordon Black, a 34-year-old staff sergeant, was convicted in Russia of theft and threatening murder. He was also having an extramarital affair - prohibited in the U.S. military - with a Russian woman named Alexandra Vashchuk, who he met during a deployment in South Korea.