On Tuesday, dozens of high-profile New York Times journalists signed onto a private letter defending the paper’s coverage of transgender issues and firing back against their own union leadership in what has become a deepening internal row over the paper’s transgender coverage.

The letter was sent to NewsGuild of New York president Susan DeCarava, taking her to task for suggesting that the paper’s coverage of transgender issues — including the adverse effects of hormonal and surgical intervention and the recent dramatic increase in gender dysphoria in girls — might have created a “hostile” workplace.

“Factual, accurate journalism that is written, edited, and published in accordance with Times standards does not create a hostile workplace,” reads the letter, which was obtained by Vanity Fair and signed by dozens of Times journalists.

The internal back-and-forth began on Wednesday, February 15, when two separate groups published open letters to the Times‘ leadership calling the paper biased in its coverage of transgender issues. The groups also singled out particular articles and authors. One letter was signed by a collection of LGBTQ organizations and the other was signed by hundreds of Times contributors.

“The Times has in recent years treated gender diversity with an eerily familiar mix of pseudoscience and euphemistic, charged language, while publishing reporting on trans children that omits relevant information about its sources,” read the letter signed by Times contributors.

The Times’ leadership didn’t take the criticism laying down. Executive editor Joe Kahn and opinion editor Kathleen Kingsbury internally rebuked the staffers who joined the effort. “We do not welcome, and will not tolerate, participation by Times journalists in protests organized by advocacy groups or attacks on colleagues on social media and other public forums,” the pair wrote.

It was after this reprimand that DeCarava decided to embroil the staff union in the debate. “Employees are protected in collectively raising concerns that conditions of their employment constitute a hostile working environment,” DeCarava wrote in a letter posted to the internal Times Guild listserv. The Guild also told Vanity Fair that Kahn and Kingsbury’s email had implied that staffers could be disciplined for criticizing the paper.

DeCarava’s entrance into the debate only stacked hostilities upon hostilities, leading to the private letter against the union leader organized by reporter Jeremy Peters.

“Every day, partisan actors seek to influence, attack, or discredit our work. We accept that. But what we don’t accept is what the Guild appears to be endorsing: A workplace in which any opinion or disagreement about Times coverage can be recast as a matter of ‘workplace conditions.’… We are journalists, not activists. That line should be clear,” Peters and company explained.

“We ask that our union work to advance, not erode, our journalistic independence,” the letter concluded.