Donald Trump has added a new item to his growing list of presidential campaign firsts: mocking a person’s physical handicap.

During a defense of his widely debunked claim that thousands of people in parts of New Jersey with large Arab populations celebrated the collapse of the World Trade Center towers on Sept. 11, 2001, Trump performed a derisive impression of New York Times reporter Serge Kovaleski — who suffers from a chronic condition that has limited the movement of his arms — at a rally in South Carolina on Tuesday night.

Citing a 2001 article written by Kovaleski that referred to people allegedly seen celebrating the attacks, Trump said it was “Written by a nice reporter.”

Trump went on, “Now the poor guy — you ought to see the guy: ‘Uhh I don’t know what I said. I don’t remember.’ He’s going, ‘I don’t remember. Maybe that’s what I said.’” As he spoke, Trump launched into an impression which involved gyrating his arms wildly and imitating the unusual angle at which Kovaleski’s hand sometimes rests. 

“We think it's outrageous that he would ridicule the appearance of one of our reporters,” said a spokeswoman for the Times. The article cited by Trump was written by Kovaleski when he worked for The Washington Post and stated that in the aftermath of Sept. 11, “Law enforcement authorities detained and questioned a number of people who were allegedly seen celebrating the attacks and holding tailgate-style parties on rooftops while they watched the devastation on the other side of the river.”

On Tuesday, after Trump’s supporters began citing the article as evidence for the candidate’s claim, Kovaleski told CNN, “We did a lot of shoe leather reporting in and around Jersey City and talked to a lot of residents and officials for the broader story. Much of that has, indeed, faded from memory … I do not recall anyone saying there were thousands, or even hundreds, of people celebrating. That was not the case, as best as I can remember.”

Kovaleski suffers from arthrogryposis, a congenital condition that limits the movement of the joints and weakens the muscles around them. As a reporter at the New York Daily News in the late 1980s and early ’90s, he covered Trump’s business exploits and met with the developer on several occasions.

Trump is not alone on his campaign in drawing unflattering attention to the physical condition of others. In 2012, when she was supporting Ted Cruz’s Senate bid, Trump’s new national spokeswoman Katrina Pierson drew flak for referring to a veteran who appeared in a video for Cruz’s opponent and who suffered back fractures and severe burns from an improvised explosive device as “deformed.”

The Trump campaign did not immediately respond to a request for comment.