It was not clear why Mueller subpoenaed Bannon and did not first ask him to sit for an interview, as Mueller had done with more than a dozen current and former White House officials who were questioned in recent months. Or that Bannon believes there is no valid privilege between executive branch officials that would preclude his testimony because both he and Mueller (appointed by the Justice Department) were and are creatures of the executive branch? Bannon's lawyer, the AP reports, was in constant contact with the White House during the interview in an attempt to find out which questions Bannon should answer and which he should avoid.
Bannon was quoted in the book making disparaging comments about the first family, the backlash to which resulted in him losing his job as chairman of Breitbart News and support from Republican mega-donors like Rebekah Mercer.
They included scathing remarks about Donald Trump Jr, the president's eldest son, for meeting during the campaign with a Russian lawyer who was said to have damaging information on Democratic candidate Hillary Clinton. It was unclear whether he would appear before the panel again.
The committee also planned to press Bannon on other "executive actions" taken by Trump that have drawn interest from congressional investigators prying into ties between Trump's campaign and Russian operatives, said the person, who wasn't authorized to speak on the record about the closed-door session and spoke to The Associated Press on condition of anonymity.
Michael Dorf, a constitutional law professor at Cornell University, said that while traditionally Congress has required a formal assertion of executive privilege in order for a witness to refuse to answer a question, more recently "we've seen people just not answer questions without asserting privilege".
Pretty much everything is off limits until the president says it's not.
Leading Kosovo Serb politician shot dead
Photo Police officers at the spot where Oliver Ivanovic was shot and killed, outside his office in Mitrovica, Kosovo, on Tuesday. According to the minister, many Ivanovic's friends who spoke with him lately noticed that he seemed anxious .
The former White House Chief Strategist featured heavily in the book which has dominated discussion this year - Fire and Fury by Michael Wolff.
"Any time you have congressional inquiries touching upon the White House, the Congress should consult with the White House prior to obtaining confidential material".
Finally, at least as portrayed by Axios, Trey Gowdy seemed interested in actually pressing Bannon with real questions and not just providing cover for the White House.
Mueller is investigating allegations that Russian Federation interfered in the 2016 campaign to try to tip the vote in Trump's favour, as well as any potential collusion by Trump's campaign with Moscow.
A spokesman for Mr Mueller's office declined to comment. If Bannon asserts his Fifth Amendment right against self-incrimination the House Intelligence Committee could either try to hold him in civil contempt or try to grant him immunity. Bannon answered: Paul Ryan and Mitch McConnell. The special counsel previously issued a grand jury subpoena for documents related to Mr Flynn's business dealings. "I found no reason whatsoever to think the president has any issues whatsoever with his thought process".
■ THE White House doctor gave Donald Trump a clean bill of mental health last night after the president asked for a check-up amid speculation about his state of mind and stability.