Senator Lindsey Graham on Friday demanded that Congress hold hearings on President Trump’s decision to withdraw American troops from Syria, a move the Republican senator strongly disagrees with.

“Especially we must NOW hear from the Pentagon about the likelihood of the rise of ISIS and the fate of our Kurdish allies in Syria,” continued the South Carolina senator, known for his hawkish positions on foreign policy.

Contrary to Trump’s assertion that ISIS has been defeated in the area, “thousands of ISIS fighters still remain and are lethal in Syria,” Graham warned.

“Is there a plan to protect our allies post withdrawal? Need answers now,” Graham said.

The Trump administration abruptly announced Wednesday that the process to bring home over 2,000 U.S. troops currently in Syria has started, a decision that was lambasted by lawmakers on both sides of the aisle. The move was apparently the last straw for Defense Secretary Jim Mattis, who announced his resignation Thursday, citing policy disagreements with Trump. The retired four-star Marine Corps general strongly opposed pulling U.S. troops out of Syria now.

Graham called the move a “huge Obama-like mistake” on Wednesday and corrected the president that ISIS is not defeated in Syria, Iraq, or Afghanistan, where Trump is reportedly also considering a troop withdrawal.

“I fear it will lead to devastating consequences for our nation, the region, and throughout the world,” he warned. “If we continue on our present course we are setting in motion the loss of all our gains and paving the way toward a second 9/11.”