President Donald Trump’s former campaign chairman, Paul Manafort, secretly worked for a Russian billionaire to advance the interests of Russian President Vladimir Putin a decade ago and proposed an ambitious political strategy to undermine anti-Russian opposition across former Soviet republics, The Associated Press has learned. Manafort’s plans were laid out in detailed documents obtained by the AP that included strategy memoranda and records showing international wire transfers for millions of dollars. How much work Manafort performed under the contract was unclear. The work appears to contradict assertions by the Trump administration and Manafort himself that he never worked for Russian interests. The disclosures come as Trump campaign advisers are the subject of an FBI probe and two congressional investigations, and they appear to guarantee that Manafort will be sought as a key witness in upcoming hearings. Investigators are reviewing whether the Trump campaign and its associates coordinated with Moscow to meddle in the 2016 campaign. Manafort has dismissed the investigations as politically motivated and misguided. The documents obtained by AP show Manafort’s ties to Russia were closer than previously revealed.