In this Tuesday, Aug. 15, 2017, file photo, U.S. Defense Secretary Jim Mattis stands as he waits for Netherlands Minister of Defense Jeanine Hennis-Plasschaert during an enhanced honor cordon at the Pentagon in Washington. U.S. As Mattis arrived in Baghdad Tuesday, he said says Islamic State militants are caught in a military vise that will squeeze them from both ends of the Euphrates River valley that bisects Iraq and Syria. (AP Photo/Alex Brandon)
In this Tuesday, Aug. 15, 2017, file photo, U.S. Defense Secretary Jim Mattis stands as he waits for Netherlands Minister of Defense Jeanine Hennis-Plasschaert during an enhanced honor cordon at the Pentagon in Washington. U.S. As Mattis arrived in Baghdad Tuesday, he said says Islamic State militants are caught in a military vise that will squeeze them from both ends of the Euphrates River valley that bisects Iraq and Syria. (AP Photo/Alex Brandon) Credit: Alex Brandon

U.S. Defense Secretary Jim Mattis said Tuesday he is confident that U.S.-backed Iraqi forces will finish off the Islamic State militants clinging to strongholds that are shrinking in size and number.

“ISIS is on the run,” Mattis told reporters after meeting with Prime Minister Haider al-Abadi and other Iraqi government leaders. “They have been shown to be unable to stand up to our team in combat.”

Mattis spoke alongside Lt. Gen. Stephen Townsend, the top U.S. commander in Iraq, who is due to finish his tour of duty here in early September.

“The fighting is tough,” Townsend said, “but the momentum is with our partners.”

Earlier, Mattis described the extremists as being trapped in a military vise that will squeeze them on both sides of the Syria-Iraq border.

Mattis had arrived in the Iraqi capital hours after President Donald Trump outlined a fresh approach to the stalemated war in Afghanistan. Trump also has pledged to take a more aggressive, effective approach against ISIS in Iraq and Syria, but he has yet to announce a strategy for that conflict that differs greatly from his predecessor’s.

The Pentagon chief told reporters before he left neighboring Jordan that the Middle Euphrates River Valley – roughly from the western Iraqi city of al-Qaim to the eastern Syrian city of Der el-Zour – will be liberated in time, as ISIS takes hit from both ends of the valley that bisects Iraq and Syria.

“You see, ISIS is now caught in-between converging forces,” he said, using an alternative acronym for the militant group that burst into western and northern Iraq in 2014 from Syria and held sway for more than two years. “So ISIS’s days are certainly numbered, but it’s not over yet and it’s not going to be over any time soon.”

Mattis referred to this area as “ISIS’s last stand.”

Unlike the war in Afghanistan, Iraq offers a more positive narrative for the White House, at least for now.

Having enabled Iraqi government forces to reclaim the Islamic State’s prized possession of Mosul in July, the U.S. military effort is showing tangible progress and the Pentagon can credibly assert that momentum is on Iraq’s side.