United States President Donald Trump on Friday confirmed that he was being investigated for his alleged role in Russian meddling into the US election last November. In a tweet, the president lashed out at special counsel Robert Mueller III, who is investigating Trump for alleged obstruction of justice. Trump again called it a “witch hunt” and said that even after seven months of investigations, nobody had been able to prove that he colluded with Russia.

Counsel Robert S Mueller III has sought interviews with senior US intelligence official Daniel Coats, the current director of national intelligence, Mike Rogers, head of the National Security Agency, and Rogers’s former deputy, Richard Ledgett, in connection with an investigation into whether Trump campaign officials colluded with Russia to influence the election. The three men have agreed to be interviewed next week.

Mueller’s office has also asked the National Security Agency for any documents or notes related to the agency’s interactions with the White House as part of the Russian investigation. The special counsel has also collected fired Federal Bureau of Investigation Director James Comey’s written accounts of his conversations with Trump. Trump’s possible contacts with Russian operatives as well as any suspicious financial activity are being examined.

James Comey, who was fired on May 9, stated before the US Senate Intelligence Committee last week that he was certain he was fired because of the president’s concerns about the Russia investigation. The White House had initially claimed that Comey’s handling of the investigation into Hillary Clinton’s private email server had been the cause of his termination. However, Trump later contradicted his administration and cited “this Russia thing” as the reason for Comey’s sacking.

Comey had confirmed during his congressional testimony on March 20 that the FBI was investigating any possible coordination between Trump and the Russians. Soon after Comey’s testimony, Trump spoke to Coats and Rogers, asking them to intervene in the matter, a request they had refused.

According to The Guardian, on Friday morning, US Deputy Attorney General Rod Rosenstein, whose memo Trump had cited initially as a reason for firing Comey said in a vague statement, “Americans should be skeptical about anonymous allegations. The Department of Justice has a long-established policy to neither confirm nor deny such allegations.” ABC News reported on Friday that Rosenstein was considering recusing himself from being a part of Mueller’s investigation.