Ben Carson initially jumped to fellow presidential candidate Donald Trump’s defense when Trump said Sunday he saw “thousands” of people in New Jersey celebrating right after the September 11, 2001 terrorist attacks. But Carson has since walked back his comment.

“I saw the film of it, yes,” Carson told reporters Monday of Trump’s claim that thousands in New Jersey, where Trump said there are “large Arab populations,” were celebrating the fall of the Twin Towers. But in a statement provided to TIME, Carson’s campaign clarified that the former neurosurgeon was remembering footage of the Middle East, not of New Jersey:

Dr. Carson does not stand behind the statement attributed to him early today regarding events surrounding 9/11. He does not believe Muslim Americans in New Jersey were celebrating the fall of the Twin Towers, rather he recalls the ample news footage of crowds in the Middle East celebrating the tragic events of 9/11. He found their jubilation inappropriate and disturbing, but did not and does not consider it representative of the Muslim American population or the Muslim population at-large.

Trump, however, isn’t backing down, even demanding an apology from the Washington Post:

Via @washingtonpost 9/18/01. I want an apology! Many people have tweeted that I am right! https://t.co/CpsMxs54qv pic.twitter.com/wrDEhXJlvR

— Donald J. Trump (@realDonaldTrump) November 23, 2015

The Post gave Trump a “four Pinocchio” rating when it fact-checked his statement, saying, “This appears to be another case of Trump’s overactive imagination.”

Read Next: Trump Draws Criticism For Saying ‘Thousands’ in New Jersey Celebrated 9/11

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Write to Tessa Berenson at tessa.berenson@time.com.