With Donald Trump on the brink of receiving classified security briefings from the Central Intelligence Agency, U.S. foreign policy figures of both parties are raising concerns about a close Trump aide’s ties to allies of Russian President Vladimir Putin. Trump’s top adviser, Paul Manafort, has spent much of his recent career working for pro-Russian forces in Ukraine, and doing complex deals for an oligarch with close ties to Putin. And while a Democratic senator has already charged Trump is not responsible enough to receive secret information, Manafort’s deep relationships with top pro-Russian figures raise special concerns.