White House Chief Strategist Steve Bannon's "60 Minutes" interview with CBS anchor Charlie Rose aired Sunday night. In their conversation, Bannon weighed in on some controversial decisions that were made while he was still serving in the White House - decisions with which he did not agree. The most egregious action taken by this administration also happens to be what he apparently views as "the biggest mistake in modern history" - the firing of FBI Director James Comey.

2. WATCH: Bannon says firing of Comey was the biggest mistake in modern political history. Also, he refuses to answer if Kushner was for it. pic.twitter.com/d0zcZgowd1 — Yashar Ali ?? (@yashar) September 11, 2017

Comey first began dominating headlines last summer, when he announced that his agency would not be pursuing criminal charges against Democratic presidential candidate Hillary Clinton, despite her having been "careless" with her use of a private email server. He was Democrats' hero, until he reopened the email probe 11 days before Election Day. His tenure under President Trump has been just as controversial, considering he was helping lead an investigation into potential collusion between Trump and Russia. When Comey sat before a Senate committee, he revealed that he took notes every time he met with the commander in chief because he was concerned Trump might lie. According to the FBI director, Trump had broken presidential protocol by asking him for loyalty.

When the president fired Comey, critics immediately and unpredictably accused him of doing so for political reasons. If Comey had not been let go, there would be no Robert Mueller special counsel investigation, Bannon adamantly told Rose.

Bannon left the Trump administration last month shortly after giving a different bombshell interview with The American Prospect, in which he distanced himself from Trump's foreign policy agenda and predicted doom for his White House enemies.

Back at Breitbart News, Bannon's main goal now is "to support Donald Trump."