A picture taken on December 30, 2018, shows a line of US military vehicles in Syria's northern city of Manbij.

President Donald Trump on Monday struggled to explain his decision to pull U.S. troops away from Syria's northern border area, where neighboring Turkey is expected to launch military operations against Kurdish soldiers there.

Trump's decision came despite recommendations of top Pentagon and State Department officials and drew sharp criticism from some of his closest allies.

In a series of tweets, Trump complained that European allies were treating America as a "sucker" by not taking responsibility for some captured Islamic State fighters. He also said the Kurds, who fought ISIS in the region, have been paid "massive amounts of money and equipment" by the U.S.

"It is time for us to get out of these ridiculous Endless Wars, many of them tribal, and bring our soldiers home," Trump tweeted. "WE WILL FIGHT WHERE IT IS TO OUR BENEFIT, AND ONLY FIGHT TO WIN."

He added: "Turkey, Europe, Syria, Iran, Iraq, Russia and the Kurds will now have to figure the situation out, and what they want to do with the captured ISIS fighters in their 'neighborhood.'"

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Late Sunday, White House press secretary Stephanie Grisham announced that the U.S. would withdraw from the Syrian-Turkish border.

"Turkey will soon be moving forward with its long-planned operation into Northern Syria. The United States Armed Forces will not support or be involved in the operation, and United States forces, having defeated the ISIS territorial 'Caliphate,' will no longer be in the immediate area," Grisham said in a statement following a call between Trump and Turkish President Recep Tayyip Erdogan.

The statement also said "Turkey will now be responsible for all ISIS fighters in the area captured over the past two years."

Trump continued to tweet about his controversial foreign policy shift as the day moved forward.

"I was elected on getting out of these ridiculous endless wars," Trump said, claiming that "the two most unhappy countries at this move are Russia & China" and assuring that "we will be focused on the big picture, knowing we can always go back & BLAST!"

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As if to calm his critics, Trump later tweeted: "If Turkey does anything that I, in my great and unmatched wisdom, consider to be off limits, I will totally destroy and obliterate the Economy of Turkey (I've done before!).

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Some of Trump's Republican allies were quick to attack the president's latest decision on the U.S. military presence in Syria. Sen. Lindsey Graham, R-S.C., one of Trump's closest confidants, went on Fox News to call the move "short-sighted and irresponsible" and said he would draw up a resolution urging Trump to reconsider.

Republican Sen. Marco Rubio of Florida said withdrawal would be a "grave mistake."

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Former Arkansas Gov. Mike Huckabee, whose daughter served as White House press secretary under Trump, said it is a "HUGE mistake" to stop supporting the Kurds. "We CANNOT abandon them," he said in a tweet.

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U.S.-backed Kurds in the region have held ISIS fighters, and have been credited with helping defeat the so-called Islamic State's caliphate. Turkey's expected incursion in northern Syria, however, has been criticized as an apparent attempt to attack the Kurds amid years of conflict between the nation and the ethnic group.

A Syrian Kurdish official said in a statement to NBC News that the U.S. has "abandoned us to a Turkish massacre."

"We can no longer fight against isis and have to defend ourselves. This could allow isis to return to the region," the official said.

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Brett McGurk, the former U.S. special envoy to the global anti-IS coalition, tweeted that Trump "provided a gift to Russia, Iran, and ISIS."

"The WH statement tonight on Syria after Trump spoke with Erdogan demonstrates a complete lack of understanding of anything happening on the ground," said McGurk, who resigned in December after Trump's previous announcement of a withdrawal from Syria.

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— CNBC's Natasha Turak contributed to this report.