President Donald Trump is doubling down on his claim that he fired former Defense Secretary James Mattis, who resigned in protest over the president's decision to withdraw all U.S. troops from Syria.

On Dec. 20, Trump initially tweeted that Mattis had retired. That evening, the Pentagon gave reporters copies of Mattis' resignation letter, which made clear the retired Marine general could no longer serve under Trump, citing irreconcilable differences.

But during a Feb. 1 interview with the New York Times, the president said he demanded and received Mattis' resignation.

“I wasn't happy with Mattis,” Trump said. “I told Mattis to give me a letter. He didn't just give me that letter. I told him.”

In his resignation letter, Mattis wrote the United States needs to be “resolute and unambiguous” towards adversaries such as Russia and China while showing respect to allies.

“Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position,” Mattis wrote.

Trump told the New York Times that Mattis' choice of words shows he was ordered to quit.

“That's why in the letter he wrote, 'You have to have your own choice,'” Trump said. “The reason he said that was because I said, 'You're just not my choice.'”

This is the second time the president has claimed that Mattis' departure was not voluntary. At a Jan. 2 cabinet meeting, Trump told reporters that he “essentially fired” Mattis for U.S. military's lack of progress in Afghanistan.

“What's he done for me?” Trump said. “How has he done in Afghanistan? Not too good. Not too good. I'm not happy with what he's done in Afghanistan. And I shouldn't be happy.

“So, I mean, I wish him well. I hope he does well. But as you know, President Obama fired him, and essentially so did I. I want results.”

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