WASHINGTON (NEXSTAR) — President Donald Trump’s newest appointee to lead the Pentagon announced plans Tuesday to withdraw more troops from Afghanistan and Iraq before Inauguration Day.

Acting Secretary of Defense Christopher Miller made official what Trump previously tweeted, saying that thousands of U.S. troops will leave the two nations, “completing the mission we started two decades ago.”

“By Jan. 15, 2021, our forces, their size, in Afghanistan will be 2,500 troops,” he said. “Our force size in Iraq will also be 2,500 (troops).”

The move was immediately met with backlash from both sides of the aisle, with lawmakers saying it will all but assure a more dangerous Middle East.

“I really am scared for our troops,” Sen. Tammy Duckworth, D-Ill., a U.S. Army National Guard veteran who received a Purple Heart after fighting in Iraq, said. “What the president is doing jeopardizes our national security, destabilizes the Middle East and really sets (in motion) a whole series of actions that will occur long after he’s gone.”

Former Defense Secretary Mark Esper warned against troop withdrawals before the president fired him last week and Republican lawmakers, including the powerful Senate Majority Leader Mitch McConnell of Kentucky, are not lining up behind Trump.

“A rapid withdrawal of U.S. forces from Afghanistan now would hurt our allies and delight, delight, the people who wish us harm,” McConnell said on the Senate floor.

“We’ve forgotten the real danger of an Afghanistan almost pre-911, which I fear it would return to again,” Rep. Adam Kinzinger, R-Ill., a former U.S. Air Force pilot who served in Afghanistan and Iraq, said.

He said the president’s move risks erasing decades of progress.

“Makes negotiations impossible and it would almost guarantee that the Taliban will hold out and then fight to take the Afghanistan government,” Kinzinger said.

But he noted there is little Congress can do to stop the withdrawal.