The interviews with the national security officials are a sign that Mueller is prioritizing the question of obstruction, says Washington Post reporter Adam Entous, and turning the focus on the president himself, not just his administration.
It was not clear whether the President was basing his tweet on direct knowledge that he is under investigation, or on reports this week that special counsel Robert Mueller is examining whether the President obstructed justice by firing Mr Comey last month amid the ongoing Russian Federation investigation. Trump later told NBC's Lester Holt he had planned to fire Comey regardless of what recommendation he received from Rosenstein and Attorney General Jeff Sessions, who has recused himself from the Russian Federation investigation.
Although President Trump proclaimed in the White House's Rose Garden that Comey's testimony proved "no collusion" and "no obstruction", the efforts by Mueller show that the investigation is moving forward.
CBS News has learned that Daniel Coats, the Director of National Intelligence, has agreed to be interviewed by the Special Counsel's office about conversations he may have had with the president about the Russian Federation investigation. It's a stance the president has repeatedly publicly stated, and one he reiterated this morning on Twitter. "Nice", Trump tweeted at 3:55 a.m. They are former Trump campaign manager Paul Manafort, his business partner Rick Gates, a national security adviser Carter Page, retired Lt. Gen. Michael Flynn and informal Trump adviser Roger Stone. Dianne Feinstein (D-CA), who said she's anxious that the President will try to fire both Mueller and Rosenstein. "I hope you can let this go".
Meanwhile there were unconfirmed reports that deputy attorney general Rod Rosenstein, who has taken charge of the Russian investigation since attorney general Jeff Sessions recused himself, could step aside from the investigation.
Mr Trump's legal team said the latest leak to the media was "outrageous". At the time, he was not under investigation but Mr Comey's revelations prompted an investigation to be started - which Mr Trump has acknowledged in Twitter posts.
Both men refused the president's request, the Post said.
It was not immediately clear what prompted the release of that statement by Rosenstein, whether it was in response to recent stories that suggested the President was under investigation for obstruction of justice, or some other reason.