Brett McGurk, special presidential envoy for the Global Coalition to Defeat ISIS, had been planning to exit his post in February 2019. But sources tell CBS News that he informed Secretary of State Mike Pompeo that he will accelerate his departure due to a strong disagreement with President Trump’s snap decision to withdraw 2,000 U.S. troops from Syria, effectively abandoning U.S. allies in the region.

McGurk submitted his resignation on Friday, just one day after Defense Secretary James Mattis quit his post citing fundamental disagreements with the commander-in-chief — including one over the importance of honoring U.S. alliances.

The special envoy was publicly left in the lurch by the president’s sudden declaration on Wednesday that he was pulling U.S. forces out of Syria, against the advice of his top national security advisers and without consulting U.S. allies.