President Donald Trump has fired FBI director James Comey, ousting the man heading serious investigations into whether his aides colluded with Russia in last year's US election.
In a shock move that drew comparisons to Watergate scandal that brought down Richard Nixon, Trump told Comey the FBI needed new leadership and he was being "terminated" immediately.
Under Comey's leadership, the FBI concluded that President Vladimir Putin approved a wide-ranging campaign to tilt the vote in Trump's favor.
His snap dismissal, ostensibly for mishandling a probe into Hillary Clinton's emails, sparked rare criticism from Republicans and allegations of a cover-up from seething Democrats who demanded an independent inquiry.
The high-stakes gambit also raised immediate comparisons to the ill-fated firings that sped the collapse of Nixon's presidency. Trump's decision to fire the FBI director is virtually unprecedented, only one director has previously been fired in the bureau's century-long history.
In a letter circulated by the White House, Trump told Comey: "You are hereby terminated and removed from office, effective immediately."
"It is essential that we find new leadership for the FBI that restores public trust and confidence in its vital law enforcement mission."
Trump also used the letter to try to distance himself from the ever-deepening scandal over Russia's involvement in the election that brought him into office.