"The counterintelligence investigation centers at least in part on the business dealings that some of the president-elect's past and present advisers have had with Russia. Mr. Manafort has done business in Ukraine and Russia. Some of his contacts there were under surveillance by the National Security Agency for suspected links to Russia's Federal Security Service, one of the officials said. Mr. Manafort is among at least three Trump campaign advisers whose possible links to Russia are under scrutiny. Two others are Carter Page, a businessman and former foreign policy adviser to the campaign, and Roger Stone, a longtime Republican operative."