It looks like the identity of the person who wrote the New York Times op-ed criticizing Donald Trump’s presidency will remain a mystery. The NYT publisher A.G. Sulzberger defended his decision Tuesday while at a gathering of news leaders in Austin, Tex.

According to the Associated Press, Sulzberger played his cards close to his chest saying that the anonymous op-ed “added to the public understanding of this administration and the actions and beliefs of the people within it.” He didn’t give a single clue about the author who wrote the piece. The only bone we have been thrown is that he or she is a senior administration official.

“We didn’t think there was any way to make that contribution without some guarantee of anonymity,” Sulzberger said. “And I think the president’s actions since the release of this piece have underscored exactly why we felt that was so important.” He added that the piece “crossed the threshold for using an anonymous source.”

Of course, Trump wasn’t happy with the op-ed. When the piece came out, he, as expected, lashed out on Twitter, saying “Does the so-called ‘Senior Administration Official’ really exist, or is it just the Failing New York Times with another phony source? If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!”

Sulzberger’s defense of printing the anonymous piece comes after he had an off-the-record meeting with Trump about the president’s anti-media rhetoric. The NYT publisher said that he regretted not having the meeting on the record. “Because if he’s not going to change his rhetoric, the biggest thing that I would hope to accomplish is to put a conversation like that on the record so that he cannot say that he was not warned if something terrible happened.”