President Trump is "not a commander-in-chief," his former anti-ISIS envoy says.

The White House announced Sunday the U.S. will "no longer be in the immediate area" of northern Syria where Turkish President Recep Tayyip Erdogan said Saturday a Turkish military incursion was "imminent." The White House's statement also said that Turkey "will now be responsible for all ISIS fighters in the area captured over the past two years."

In response, Brett McGurk, former special presidential envoy for the global coalition to counter the Islamic State, blasted Trump in a Twitter thread, saying is he "not a commander-in-chief" and that he "makes impulsive decisions with no knowledge or deliberation."

Donald Trump is not a Commander-in-Chief. He makes impulsive decisions with no knowledge or deliberation. He sends military personnel into harm’s way with no backing. He blusters and then leaves our allies exposed when adversaries call his bluff or he confronts a hard phone call. — Brett McGurk (@brett_mcgurk) October 7, 2019

McGurk writes that the White House's statement "demonstrates a complete lack of understanding of anything happening on the ground," as contrary to what it suggests, the U.S. is "not holding any ISIS detainees" but rather they "are all being held by the [Syrian Democratic Forces], which Trump just served up to Turkey." McGurk also says that "Turkey has neither the intent, desire, nor capacity to manage" 60,000 detainees, and "believing otherwise is a reckless gamble with our national security."

"Bottom line: Trump tonight after one call with a foreign leader provided a gift to Russia, Iran, and ISIS," he concludes.

McGurk, who also served in the Obama and Bush administrations, in December left his position two months early after Trump announced he would withdraw troops from Syria, in a Washington Post op-ed later saying that Trump in doing so is giving ISIS "new life." Trump subsequently dismissed him in a tweet as "Brett McGurk, who I do not know." Brendan Morrow