President TrumpDonald John Trump2020 Democrats spar over socialism ahead of first debate Senate passes .5 billion border bill, setting up fight with House 'Teflon Don' avoids the scorn of the 'family values' GOP — again MORE defended his recent foreign policy decisions on Saturday and criticized personnel from his national security team who resigned this week.

Brett McGurk announced his resignation as Trump's envoy to the coalition fighting the Islamic State in Iraq and Syria (ISIS) earlier Saturday, following in the footsteps of Defense Secretary James MattisJames Norman MattisNew Defense chief: Our 'priorities remain unchanged' The Hill's 12:30 Report: Trump targets Iran with new sanctions Trump urged to quickly fill Pentagon post amid Iran tensions MORE, who announced his own resignation on Thursday. Both men are said to have had differences with the president over Trump's plan to withdraw U.S. forces stationed in Syria battling ISIS in the region.

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In a tweet, Trump said he did not know McGurk and that McGurk's tenure was set to expire in February, accusing him of making a larger issue out of his exit over the president's new orders for U.S. deployments in the Middle East.

News reports Friday noted that McGurk was planning to leave the Trump administration in February, but accelerated his decision due to Trump's order.

"Brett McGurk, who I do not know, was appointed by President Obama in 2015. Was supposed to leave in February but he just resigned prior to leaving. Grandstander? The Fake News is making such a big deal about this nothing event!" Trump tweeted.

In a second tweet, the president knocked media coverage of his decision to withdraw troops from Syria, which multiple news outlets reported was made without first consulting senior officials at the Department of Defense.

"If anybody but your favorite President, Donald J. Trump, announced that, after decimating ISIS in Syria, we were going to bring our troops back home (happy & healthy), that person would be the most popular hero in America. With me, hit hard instead by the Fake News Media. Crazy!" the president wrote.

Trump later issued a third message, this time aimed at Mattis directly, which asserted that Mattis had been "ingloriously fired" by Trump's predecessor, former President Obama, while appearing to criticize a section of Mattis's official resignation letter detailing the need for close relationships with U.S. allies.

"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 night.

Mattis was previously replaced as head of U.S. Central Command by Obama in 2013, reportedly over the two men's differences regarding Iran. In his resignation letter this week, the Defense secretary cited the need for a secretary who more closely aligned with the president's views as a reason.

McGurk, meanwhile, has offered no public statements since his resignation, but just days ago he told reporters at a State Department press briefing that it would be "reckless" to unilaterally withdraw from the region.

“I think it's fair to say Americans will remain on the ground after the physical defeat of the caliphate, until we have the pieces in place to ensure that that defeat is enduring," McGurk said at the time.

"It would be reckless if we were just to say, well, the physical caliphate is defeated, so we can just leave now. I think anyone who's looked at a conflict like this would agree with that," he added at the news conference.

— This report was updated on Dec. 23 at 7:25 a.m.