Sean Spicer offers rare apology over Adolf Hitler remarks

White House Press Secretary Sean Spicer has done something rare for a senior adviser to President Donald Trump and for Trump himself. He apologized.

"I mistakenly used an inappropriate, insensitive reference to the Holocaust," Spice said. "I apologize. It was a mistake to do that."

The rare mea culpa came regarding Spicer's inaccurate reference to Adolf Hitler Tuesday. Spicer ignited a furious backlash when he suggested that Syrian President Bashar al-Assad had committed atrocities worse than Hitler's.

Specifically, Spicer argued that the Nazi dictator had not used chemical weapons, which was false. Hitler used large amounts of lethal chemicals including Zyklon B to kill Jews and others in gas chambers during the Holocaust. Six million Jews and others were exterminated by the Nazis.

RELATED: Twitter reacts to Spicer saying Hitler didn't use "chemical weapons"

Spicer tried to walk back his statements Tuesday afternoon but the backlash intensified. He had been attempting to defend Trump's decision to order a missile strike in Syria after American officials concluded that Assad had used sarin gas to attack a rebel-held area of Idlib province last week, killing dozens of civilians including many children.

Spicer initially told reporters, "We didn't use chemical weapons in World War II. You know, you had someone as despicable as Hitler who didn't even sink to using chemical weapons." Spicer followed up by admitting that Hitler used chemical agents but not in the same way as Assad. "I think when you come to sarin gas, he was not using the gas on his own people the same way that Assad is doing," Spicer said. But an estimated 160,000 to 180,000 Jews killed by the Nazis had been residents of Germany, according to the New York Times.

One of the initial denunciations came from Deborah Lipstadt, a historian of the Holocaust and professor at Emory University in Atlanta, who told the New York Times, "Historically, it's just wrong." Lipstadt added that Spicer "should not be making comparisons. It's, at the best, not thought out, and at the worst, shows a latent anti-Semitism."

House Democratic Leader Nancy Pelosi, D-Calif., urged President Trump to fire Spicer.

On Tuesday night, Spicer apologized in an interview with CNN. "I was trying to draw a comparison for which there shouldn't have been one," he said. Spicer expressed regret that he was distracting attention away from topics that Trump wanted to talk about, such as his decisive action in launching the missile attack in Syria last week.

Spicer also made a key error Monday when he said Trump would retaliate against Syria again not only if the regime used chemical weapons but also barrel bombs. "If you gas a baby, if you put a barrel bomb into innocent people, I think you will see a response from this president," Spicer said. He apparently was unaware or overlooked the fact that barrel bombs are already used, and deployed frequently, by the Assad government to kill civilians and rebels.

Spicer has been a lightning rod since he started giving White House media briefings as press secretary in January. On the first full day of the new administration, he argued that the crowd at Trump's inauguration was the largest ever to witness a presidential swearing-in, which was wrong. He refused to take questions from the media at that point and abruptly left the podium.

Copyright 2017 U.S. News & World Report

RELATED: White House Press Secretary Sean Spicer