On “Fox & Friends” the next morning, the co-host Brian Kilmeade said he was “elated” by the news, only to be scolded by Geraldo Rivera, who pointed to false intelligence peddled by the George W. Bush administration to justify the Iraq war.

“Don’t for a minute start cheering this on,” Mr. Rivera, a Fox News correspondent, told the hosts.

Mr. Bannon, the former chief of Breitbart News, now runs a pro-Trump podcast, “War Room: Impeachment.” In the interview, he said he was concerned that a burgeoning conflict in Iran could threaten Mr. Trump’s support among “working-class, middle-class people, particularly people whose sons and daughters actually fight in these wars,” a group that believed the president opposed significant foreign intervention.

“Why was it necessary to kill this guy and to kill him now and to exacerbate the military issues, given the fact that President Trump looks to us as someone who’s not trigger happy?” Mr. Bannon said, paraphrasing a question he said he was hearing from independent voters.

“That still has to be explained,” Mr. Bannon continued. “I don’t know if it’s the president addressing the nation. I don’t know if it’s the president getting on ‘Fox & Friends.’ But clearly, at some point in time, the president’s got to walk through not just what his logic was, but also where he wants to take this.”

Indeed, part of the problem for conservative media commentators was the lack of guidance from the White House, which has been slow to settle on a public narrative around General Suleimani’s death.

In 2003, as the Bush administration prepared for a conflict in Iraq, White House officials took pains to build support among allies and media commentators for an invasion. In 2020, the Trump administration seems to be attempting the reverse: retroactively arguing its case even as the world grapples with the consequences of a provocative military strike.

Without providing specifics, Trump aides have referred to evidence from intelligence agencies about an imminent threat from Iran — the same intelligence agencies that Mr. Trump and his media surrogates have attacked for three years as biased and prone to fabricating evidence.