Newly surfaced FBI documents reportedly show that the bureau opened a counter-intelligence investigation into whether Donald Trump himself was acting as an agent of Russia, launched in the aftermath of his sacking of FBI director James Comey in May 2017. The inquiry, one of the most sensitive ever undertaken by the FBI into a sitting president, examined whether Trump's actions – including the Comey dismissal – were connected to Russian interests, and it has remained a flashpoint in arguments over the legitimacy of the wider Trump-Russia probe.

The existence of such an investigation was first reported publicly in 2018, but the newly disclosed material is said to provide fresh detail on how and why the FBI came to open the case. The documents add to years of dispute between Trump and the bureau over the Russia inquiry, which he has long dismissed as a politically motivated "witch hunt", and are likely to reignite scrutiny of the FBI's conduct during that period as well as renewed political reaction from the White House.