ABOARD THE USS BATAAN (AP) — Over the past eight months, the United States has poured more than 20,000 additional troops into the Middle East to counter the escalating threat from Iran that peaked with the recent missile attack on American forces in Iraq.

Despite President Donald Trump’s pledge to bring troops home, the top U.S. commander in the Middle East on Thursday said the most recent forces to enter the region could be there for “quite a while.”

“You’re here because I requested that you come,” Marine Gen. Frank McKenzie told sailors and Marines aboard the USS Bataan amphibious assault ship, his voice booming over the ship’s loudspeaker. “I’m not sure how long you’re going to stay in the theater. We’ll work that out as we go ahead. Could be quite a while, could be less than that, just don’t know right now.”

The Bataan and two other U.S. warships moved into the Middle East on Jan. 11. By Thursday, they were in the north Red Sea, roughly 50 miles south of the Sinai Peninsula. They are the latest additions to America’s troop presence in the region. Since May, their numbers have grown from about 60,000 to more than 80,000.

Those increased deployments came despite two significant hurdles: Trump’s persistent pledge to end the wars and bring troops home, and U.S. Defense Secretary Mark Esper’s insistence that U.S. forces be shifted to the Asia-Pacific as a bulwark against threats from China.

In making its case for troops in the Middle East, the U.S. military points to Iran’s Jan. 8 launch of as many as two dozen ballistic missiles at two Iraqi bases where U.S. troops were stationed. The attack was in retaliation for a U.S. drone strike that killed Qassem Soleimani, Iran’s top general.

“Iran continues to pose a very real threat,” McKenzie told reporters traveling with him to the Bataan. “I do believe that they are deterred right now, at least from state-on-state actions by our response. And so I think that while that threat remains, I think we’re in a period where they’re certainly not seeking to escalate anything.”