Donald Trump fumed at a "witch hunt" investigation into his campaign's dealings with Russia, as special counsel Robert Mueller's secretive probe entered its second year.
"Congratulations America, we are now into the second year of the greatest Witch Hunt in American History" Trump said in a series of angry tweets to mark the anniversary.
A year on from the ex-FBI director's appointment, Mueller's work still thoroughly dominates US politics and menaces Trump's presidency like a churning storm.
White House officials - many of whom have themselves been called to testify and been forced to "lawyer up" - complain bitterly that they cannot get on with the people's work.
Congratulations America, we are now into the second year of the greatest Witch Hunt in American History...and there is still No Collusion and No Obstruction. The only Collusion was that done by Democrats who were unable to win an Election despite the spending of far more money!— Donald J. Trump (@realDonaldTrump) May 17, 2018
Wow, word seems to be coming out that the Obama FBI “SPIED ON THE TRUMP CAMPAIGN WITH AN EMBEDDED INFORMANT.” Andrew McCarthy says, “There’s probably no doubt that they had at least one confidential informant in the campaign.” If so, this is bigger than Watergate!— Donald J. Trump (@realDonaldTrump) May 17, 2018
Despite the disgusting, illegal and unwarranted Witch Hunt, we have had the most successful first 17 month Administration in U.S. history - by far! Sorry to the Fake News Media and “Haters,” but that’s the way it is!— Donald J. Trump (@realDonaldTrump) May 17, 2018
Little is known about Mueller's work, which even close observers refer to as a "black box."
But once in a while, a court filing reveals targets, charges and methods and jolts official Washington like a detonation.
Trump's former campaign chairman Paul Manafort, his first national security advisor Michael Flynn and an assortment of campaign aides have all been caught in the snare, variously pleading guilty, cutting a plea deal or fighting the case in court.
But the big questions remain unanswered: Did Trump's campaign collude with the Kremlin to skew the 2016 election? What did the president know and when did he know it? Did he obstruct justice? Can a sitting president be indicted?
Those questions may only be answered when Trump himself sits down for an interview under oath - something he has professed to want to do, but has yet to act upon.
As the subpoenas, indictments and guilty pleas have rolled in, Trump has screamed innocence.
"There is still No Collusion and No Obstruction," he said while turning allegations back on his critics.
"The only Collusion was that done by Democrats who were unable to win an Election despite the spending of far more money!" he claimed.
Ever the salesman, the 72-year-old president has tried to assuage supporters with claims of an epoch-making presidency.
"Despite the disgusting, illegal and unwarranted Witch Hunt, we have had the most successful first 17 month Administration in U.S. history - by far!"
"Sorry to the Fake News Media and 'Haters,' but that's the way it is!"
Such claims aside, Trump has often appeared transfixed by the Mueller probe.
He has repeatedly sought to try the case in the court of public opinion - muddying the waters, smearing investigators and meddling behind the scenes.
But his instinct to "fight back" has itself posed political problems and perhaps flirted with illegality.
He fired FBI director James Comey, demanded his attorney general step in, mused publicly about firing Mueller and called on him to wrap it up.
And while congressional allies and friendly media such as Fox News have run interference for the White House, a sphinxlike Mueller has appeared determined to live by the dictum that "the wheels of justice turn slowly, but grind exceedingly fine."
Ahead of pivotal 2018 legislative elections, Democrats have wavered between a desire to use the probe as a political cudgel to beat Trump and fears of politicizing the probe.
"It's not a witch hunt when 17 Russians have been indicted. It's not a witch hunt when some of the most senior members of the Trump campaign have been indicted," said top Senate Democrat Chuck Schumer.
"The volume of mistruth, the weight of all the distortion and fabrication, is hurting our democracy."
Polls show that Republicans are in danger of losing control of the House of Representatives, the very body that would begin any impeachment proceedings against Trump.
It remains unclear whether Mueller's probe will conclude before Americans go to the polls again this November.
Trump, keen to keep up the pressure, on Thursday leapt on a New York Times report that at least one government informant met two Trump campaign advisers.
"Wow, word seems to be coming out that the Obama FBI 'SPIED ON THE TRUMP CAMPAIGN WITH AN IMBEDDED INFORMANT,'" the president tweeted, misspelling the word "embedded."
"As these revelations are making their way forward, it looks like the Trump campaign may in fact have been surveilled," White House counsellor to the president Kellyanne Conway told Fox News Thursday. "As the president likes to say, we'll see what happens."
"I think those who have been digging and conjecturing for over a year should be careful what they wish for."
White House press secretary Sarah Sanders said Trump's views were well known.
"I'm not sure how we could be any more clear and certainly not sure how the president could be any more clear about his beliefs in his opinion," she said.