President Donald Trump rang in the one-year anniversary of the appointment of special counsel Robert Mueller by slamming the probe into his campaign's ties to Russian during the 2016 election.

"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," Trump tweeted. "The only Collusion was that done by Democrats who were unable to win an Election despite the spending of far more money!"

Thursday marked one year since Deputy U.S. Attorney General Rod Rosenstein appointed Mueller, a former FBI director, to be a special counsel overseeing the investigation.