Donald Trump. REUTERS/Rainier Ehrhardt Donald Trump claims that "thousands" of people in New Jersey were "cheering" amid the September 11, 2001, terrorist attacks on US soil.

In an interview on ABC's "This Week" on Sunday, Trump doubled down on his assertion that he saw people in New Jersey — where the real-estate mogul claims there are "large Arab populations" — cheering as the World Trade Center came down.

"There were people that were cheering on the other side of New Jersey, where you have large Arab populations. They were cheering as the World Trade Center came down," Trump said on Sunday. "I know it might be not politically correct for you to talk about it, but there were people cheering as that building came down — as those buildings came down. And that tells you something. It was well-covered at the time."

Trump first made the claim at a Birmingham, Alabama, rally on Saturday.

"I watched when the World Trade Center came tumbling down, and I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down,” he said.

As The New York Times reported, it's unclear to what Trump was referring. Images were broadcast of cheering in Middle Eastern countries, but local officials had to dispute a prevalent internet rumor that Muslims were cheering in Paterson, New Jersey.

Trump has recently embraced a number of hard-line, provocative positions specifically targeting Muslims in the US.

After the Paris attacks, for which the group ISIS has claimed responsibility, Trump repeatedly said the US needs surveillance of "certain mosques." He criticized New York Mayor Bill de Blasio's support for ending a New York City Police Department surveillance program that placed plainclothes officers undercover in mosques and Muslim student groups.

"I don’t want to close mosques — I want to surveil mosques. I want mosques surveilled. We were doing it New York City for a while until the worst mayor that New York City has ever had got elected," Trump said on Sunday, referring to de Blasio.

Trump also said on Sunday that he would bring back waterboarding if the US captured ISIS members, and did not rule out whether he would create a national database of Muslims.