NBCUniversal told the Trump campaign Thursday that it would not air an ad that previously appeared on some of NBC's channels unless changes are made.

An NBC official said that the ad titled "Ukraine," which focused on former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE and referenced unsubstantiated claims about corrupt practices Biden supposedly engaged in, was pulled from NBC's ad lineup until the Trump campaign makes unspecified changes. NBC would not confirm what changes it requested from the campaign.

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It was unclear whether the changes specifically involved claims the Trump campaign has made about Biden's past contacts with Ukrainian officials. The Trump campaign, meanwhile, issued a statement to the Journal defending the content of its ads and submitted a different advertisement to NBC, which it began airing.

“Our ads are 100 percent accurate,” Tim Murtaugh, a campaign spokesman, told the newspaper. “The discussions with NBC had nothing to do with the facts as presented in the ad. We have no further comment on those conversations.”

The ad reportedly ran once on both MSNBC and Bravo, before the network completed a review of the video and stated that it would require changes before appearing on NBC's main channel.

NBC's decision to pull the ad comes after rival news network CNN issued a statement declining to run the ad, explaining that derogatory remarks aimed at CNN reporters in the ad as well as "demonstrably false" assertions made in the ad resulted in the piece not meeting CNN's standards.

“CNN is rejecting the ad, as it does not meet our advertising standards,” a representative told The Hill last week. “Specifically, in addition to disparaging CNN and its journalists, the ad makes assertions that have been proven demonstrably false by various news outlets, including CNN.”

Fox News, on the other hand, refused a request from the Biden campaign to cease airing the ad, calling such a decision akin to censorship.

“We are not in the business of censoring ads from candidates on either side of the aisle," Fox's statement read. "Vice President Joe Biden has a standing invitation to appear on any of our platforms.”