"The Mueller probe should never have been started in that there was no collusion and there was no crime. It was based on fraudulent activities and a Fake Dossier paid for by Crooked Hillary and the DNC, and improperly used in FISA COURT for surveillance of my campaign. WITCH HUNT!" Trump said on Twitter.
Robert Mueller is investigating alleged Russian interference in the 2016 election and accusations of collusion with the Trump campaign.
The memo also alleged the FBI and DOJ staff had abused the Foreign Intelligence Surveillance Act (FISA) in the investigation of Trump's campaign. Democrats have refuted such allegations.
Both Trump and the Kremlin have denied any purported collusion, and Moscow has called the accusations of interference in the election "absurd."