Christopher Steele, who wrote reports on compromising material Russian operatives allegedly had collected on U.S. President-elect Donald Trump, is a former officer in Britain's Secret Intelligence Service, according to people familiar with his career. Former British intelligence officials said Steele spent years under diplomatic cover working for the agency, also known as MI6, in Russia and Paris and at the Foreign and Commonwealth Office in London. After he left the spy service, Steele supplied the U.S. Federal Bureau of Investigation with information on corruption at FIFA, international soccer's governing body....