For the second time in 10 months, President Donald Trump has acquiesced to Turkish demands to move U.S. forces out of the way of a planned offensive against the Kurdish fighters who have fought and died alongside U.S. troops to destroy ISIS's former caliphate in Syria.

The White House announced at 11 p.m. on Sunday that Trump had agreed to withdraw U.S. troops from northeast Syria after speaking with Turkish President Recep Tayyip Erdoğan, whose military will now supposedly to take custody of the tens of thousands of ISIS fighters and their families currently being held by the Syrian Democratic Forces.

In a series of tweets on Monday, Trump claimed that the majority of ISIS prisoners are foreign fighters from Europe, but European countries refused to repatriate them “thinking, as usual, that the U.S. is always the 'sucker.'”

“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,'” Trump tweeted. “They all hate ISIS, have been enemies for years. We are 7000 miles away and will crush ISIS again if they come anywhere near us!”

Amid an outpouring of criticism on Monday about leaving the Kurds to fend for themselves, Trump appeared to warn Turkey against going too far by threatening to “obliterate” its economy if it does anything that “I, in my great and unmatched wisdom, consider to be off limits.”

As late as Friday afternoon, the Defense Department's official position was the United States was working with Turkish troops to create a “security mechanism” in northeast Syria that would be free of the Kurdish People's Protection Units, or YPG, which Turkey considers to be a terrorist group.

“Right now, we're focused on making the security mechanism functional in northeast Syria,” Defense Secretary Mark Esper told reporters on Friday. “I had a long conversation with my counterpart [Turkish Defense Minister Hulusi Akar] yesterday, and this was the specific focus of our discussion, and I made very clear to him and he agreed as well that we need to make the security mechanism work.”

Defense officials insisted on Monday that Trump's decision had not caught the Pentagon by surprise. Esper and Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff worked with the Secretary of State Mike Pompeo and other top officials on the issue.

“The Department of Defense made clear to Turkey – as did the President – that we do not endorse a Turkish operation in northern Syria,” Chief Pentagon spokesman Jonathan Hoffman said in a Monday statement. “The U.S. armed forces will not support, or be involved in any such operation.”

It was not immediately known if the White House or U.S. military alerted Kurdish fighters about the president's decision ahead of time. SDF spokesman Mustafa Bali tweeted his outrage at the impending withdrawal of U.S. forces from northwest Syria, claiming it will turn the region into a “war zone.”

“We are not expecting the US to protect NE #Syria,” Bali tweeted on Monday. “But people here are owed an explanation regarding security mechanism deal, destruction of fortifications and failure of US to fulfill their commitments.”

Lawmakers on both sides of the aisle expressed concern and confusion about the president abandoning the U.S. military's Kurdish allies. Sen Lindsey Graham, (R-S.C) tweeted that the withdrawal of U.S. troops could help Iran to dominate Syria and ensure that ISIS is able to rejuvenate itself.

“By abandoning the Kurds we have sent the most dangerous signal possible – America is an unreliable ally and it's just a matter of time before China, Russia, Iran, and North Korea act out in dangerous ways,” tweeted Graham, who had helped persuade Trump to rethink his initial decision in December to pull all U.S. troops out of Syria.

The president had announced in December that the U.S. mission in Syria was accomplished because ISIS had been defeated, so he was going to withdraw all U.S. troops from the country. Then-Defense Secretary James Mattis was reportedly so livid at Trump's decision to leave Kurdish fighters at the mercy of the Turks that he resigned in protest.

For Marine veteran Rep. Seth Moulton, who deployed four times to Iraq, Trump's decision to withdraw U.S. troops from northeast Syria represents a betrayal.

“'We've got your back;' these are words every American veteran knows, we say that to one another, and we say it to our allies,” Moulton (D-Mass.) said in a statement. “But Trump says it to our enemies: Putin, Assad and Kim Jong-Un. Now he's giving up our Kurdish allies–who've been some of the toughest fighters in Iraq for three decades–because an authoritarian Turkish president, more aligned with Russia than U.S. allies, asked him for a favor.

“This decision will embolden Russia, Iran, ISIS, Syria and our other enemies in the region and around the globe by showing them that America doesn't keep its promises, doesn't stand up for our friends, and follows the whims of a Commander in Chief who doesn't know a thing about serving his country.”

UPDATE: This story was updated on Oct. 7 with comments from Rep. Seth Moulton (D-Mass.)