Republican presidential candidate Donald Trump has taken his feud with Fox News, specifically host Megyn Kelly, to the next level. Craig Barritt/Getty Images for Cosmopolitan Magazine and WME Live

Roger Ailes, chairman and CEO of Fox News Channel, publicly demanded Tuesday that GOP front-runner and real estate mogul Donald Trump apologize to Fox News host Megyn Kelly, calling remarks from Trump on Monday “unprovoked” and “disturbing.”

The shot at Trump is the latest in the public feud between Trump and Ailes’ channel, which began after Trump slammed Kelly for her pointed questions during the first Republican presidential debate on Aug. 6. Before Monday, the two parties appeared to have reached a truce via backroom dealing.

But after Kelly returned from a weeklong vacation Monday, Trump pounced again via his favorite megaphone, Twitter:

Ailes responded on Tuesday with the following statement provided by Fox News to International Business Times. He called Trump’s attack “disturbing” and demanded an apology:

Donald Trump's surprise and unprovoked attack on Megyn Kelly during her show last night is as unacceptable as it is disturbing. Megyn Kelly represents the very best of American journalism and all of us at FOX News Channel reject the crude and irresponsible attempts to suggest otherwise. I could not be more proud of Megyn for her professionalism and class in the face of all of Mr. Trump’s verbal assaults. Her questioning of Mr. Trump at the debate was tough but fair, and I fully support her as she continues to ask the probing and challenging questions that all presidential candidates may find difficult to answer. Donald Trump rarely apologizes, although in this case, he should. We have never been deterred by politicians or anyone else attacking us for doing our job, much less allowed ourselves to be bullied by anyone and we’re certainly not going to start now. All of our journalists will continue to report in the fair and balanced way that has made FOX News Channel the number one news network in the industry.

Roger Ailes, Chairman & CEO FOX News

Trump responded with a statement, obtained by Politico, standing by his gibes at Kelly.

"I totally disagree with the Fox statement," Trump said. "I do not think Megyn Kelly is a quality journalist. I think her questioning of me, despite all of the polls saying I won the debate, was very unfair. Hopefully in the future I will be proven wrong and she will be able to elevate her standards to a level of professionalism that a network such as FOX deserves."

With his recent war on Fox, Trump has forced Ailes into the public eye. Instead of the reprimand coming from, say, a vice president or a spokesman, it came from Ailes, who has the power to hit back with equal and opposite force when Trump embarrasses or ridicules the network.

The ex-reality-TV star appears comfortable burning Fox again after patching things up in the post-debate fallout -- only a week ago, both men declared the spat over and done with. “Roger Ailes just called,” Trump tweeted. “He is a great guy & assures me that ‘Trump’ will be treated fairly on @FoxNews . His word is always good!”

Ailes put out his own statement saying he and Trump had "a blunt but cordial conversation."

It remains to be seen how they’ll settle their beef this time.

For his part, Fox owner Rupert Murdoch has stopped bothering to hide his displeasure with Trump, tweeting in July, “When is Donald Trump going to stop embarrassing his friends, let alone the whole country?” Just this week, the media mogul advocated that billionaire and former New York Mayor Mike Bloomberg run for president to counter Trump.