Carter Page, who served as a foreign-policy adviser to Donald Trump’s campaign, was known to U.S. counterintelligence officials for years before he became a prominent figure in a dossier of unverified research about the future president’s ties to Russia.What prompted the FBI to suspect that Mr. Page was acting as an agent of Russia?.. the former Trump aide has been known to U.S. counterintelligence officials dating back to at least 2013, nearly three years before he joined the Trump campaign... Mr. Page’s dealings with Russia date back to more than a decade before Mr. Trump ran for president and his opponents began crafting the dossier.For three years, starting in 2004, Mr. Page was living in Moscow, where he opened an office for the investment banking firm Merrill Lynch & Co. He also served as an adviser on “key transactions” involving the Russian state-owned energy company PAO Gazprom and RAO UES, the Russian state-controlled electricity monopoly, according to Mr. Page’s biography... In January 2013, Mr. Page was in New York at an Asia Society event on China and energy development, when he met Victor Podobnyy, a junior attaché at the Russian consulate in New York City who was in the audience.. March 2013, Mr. Page met with Mr. Podobnyy again over coffee or a Coke, he told the House panel in his testimony. Mr. Page, asked why he had sought out Mr. Podobnyy a second time, said he wanted to practice his Russian... He was interviewed by FBI counterintelligence agent Gregory Monaghan and another FBI agent, who were investigating whether Mr. Podobnyy was a Russian intelligence agent.. In 2015, Mr. Podobnyy was charged with posing as a U.N. attaché under diplomatic cover while trying to recruit Mr. Page as a Russian intelligence source... The criminal complaint filed by U.S. federal prosecutors alleged Mr. Podobnyy was an agent for the SVR, Russia’s foreign intelligence service. The complaint also detailed Mr. Podobnyy’s discussion in April 2013 with Igor Sporyshev, a second alleged SVR agent posing as a Russian trade representative, about efforts to recruit “a male working as a consultant in New York City.” Mr. Podobnyy was afforded diplomatic immunity and left the country... Mr. Page had provided the Russians with documents, which Mr. Page said were “nothing more than a few samples from the more detailed lectures” he was preparing for a course he was teaching at New York University at the time... Over the course of the campaign, Mr. Page traveled to Russia at least twice and kept top Trump campaign advisers abreast of his travels.. In the speech, he criticized the U.S. and European states for their behavior toward states of the former Soviet Union for their “often hypocritical focus on ideas such as democratization, inequality, corruption and regime change.”.. He declined to answer questions after the speech about U.S. politics, saying that the purpose of his speech was academic, and refused to meet with reporters, leaving the auditorium through an exit backstage... Mr. Page told the House that while in Moscow, he “briefly said hello” to Arkady Dvorkovich, deputy prime minister of Russia, and met with Andrey Baranov, head of investor relations at Russian oil giant PAO Rosneft... Before hiring Mr. Steele, the firm’s research had been paid for by a conservative news outlet that opposed Mr. Trump... Mr. Page’s name surfaced repeatedly in the fall of 2016 in classified briefings given to high-level members of Congress, according to people familiar with the matter. That was around the same time the FBI and the Justice Department were applying for a surveillance warrant against Mr. Page in the FISA court.