Trump claimed he read James Mattis' resignation letter -- but didn't know it was critical of him until he saw it on TV: report
Donald Trump speaks to Jim Mattis (Pentagon)

A bombshell report in the New York Times that details the split between President Donald Trump and Defense Secretary James Mattis, who was once one of his closest advisers.

“One aide said that although Mr. Trump had already seen the resignation letter when he praised Mr. Mattis, the president did not understand just how forceful a rejection of his strategy Mr. Mattis had issued,” the Times reported.

When Trump received the resignation letter he tweeted out his overwhelming support for Mattis for his service and the work he'd done. He called the resignation a "retirement" that Mattis deserved.

"General Jim Mattis will be retiring, with distinction, at the end of February, after having served my Administration as Secretary of Defense for the past two years. During Jim’s tenure, tremendous progress has been made, especially with respect to the purchase of new fighting equipment. General Mattis was a great help to me in getting allies and other countries to pay their share of military obligations. A new Secretary of Defense will be named shortly. I greatly thank Jim for his service!" Trump tweeted.

The resignation letter was then released to the public, where cable news pundits pointed out how critical of Trump it was.

"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 said in the two-page letter.

Two days after the president allegedly read the resignation letter and tweeted his positive support, Trump took a 180-degree turn to attack the general.

"When President Obama ingloriously fired Jim Mattis, I gave him a second chance. Some thought I shouldn’t, I thought I should. Interesting relationship-but I also gave all of the resources that he never really had. Allies are very important-but not when they take advantage of U.S.," Trump tweeted Saturday.

It was reported that the president read the letter, it's unclear if he understood what he was reading at the time. Mattis will be replaced by a former Boeing executive.