President Donald Trump's mangled Syria pullout has breathed “new life” into ISIS, the very terror group Trump vowed to destroy before declaring it defeated, the former U.S. official in charge of the ISIS fight said.

Brett McGurk, the former special presidential envoy in charge of the 79-nation coalition to fight ISIS, wrote a blistering op-ed in the Washington Post exposing the chaos at the Pentagon and among US allies after Trump's snap decision to leave Syria.

McGurk, along with former Secretary of Defense Jim Mattis, resigned following Trump's move. Since then, Trump has hit back at the former officials, calling McGurk a “grandstander,” and later claiming he had fired Mattis, rather than Mattis resigning.

But McGurk says that Trump totally surrendered the U.S.'s role in Syria to Turkey after a phone call with Turkish President Recep Tayyip Erdogan, and that the decision wounded the U.S.'s credibility and standing with its allies.

Trump's declaration that U.S. had finally defeated ISIS and the only reason for U.S. forces in Syria was to fight the terror group directly contradicted statements from his own State Department, Pentagon, and national security advisor.

According to McGurk, Trump's decision will expose the Syrian Democratic Forces — a group of 60,000 regioinal Kurds, Arabs, and Christians that have won hard-fought battles against ISIS on the ground, sometimes fighting shoulder-to-shoulder with US troops — will now be exposed to Turkey's wrath, as they back opposing forces and veiw the Kurdish elements of the SDF as terrorists.

“My counterparts in coalition capitals were bewildered. Our fighting partners in the SDF, whom I had visited regularly on the ground in Syria, expressed shock and then denial, hoping Trump would change his mind,” wrote McGurk.

“The president's decision to leave Syria was made without deliberation, consultation with allies or Congress, assessment of risk, or appreciation of facts,” he continued, then concluding that he could not maintain his integrity while carrying out Trump's order, prompting his resignation.In conclusion, McGurk says that Trump has given ISIS and opponents of the US “new life” by pulling out of Syria in a move that will “precipitate chaos and an environment for extremists to thrive.”

Trump's Syria pull out also coincided with the death of four U.S. citizens at a restaurant in what was considered a safe part of Syria under US control. The ISIS-claimed attack doubled the U.S. death toll in Syria, which had only claimed two lives since the campaign launched in 2015.

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