Iraqi government forces drive a tank on June 22, 25 miles west of Qayyarah, where they seized control of an airfield July 9. (Mahmud Saleh/AFP via Getty Images)

BAGHDAD — Defense Secretary Ashton B. Carter said Monday that the Pentagon will deploy an additional 560 U.S. troops to Iraq, widening the U.S. military campaign against the Islamic State after Iraqi security forces seized a key airfield over the weekend.

Army Lt. Gen. Sean MacFarland, the top U.S. commander in Iraq, said that the additional troops will “predominantly” be assigned to the newly recaptured air base, installing everything from additional security measures to communications gear. Qayyarah Air Base is considered an important springboard to take back the city of Mosul, which is the de facto capital of the Islamic State in Iraq and about 40 miles north of the airfield.

The decision to deploy more service members will elevate the number of U.S. troops the Pentagon counts in Iraq to 4,647. Unofficially, that figure is probably closer to 6,000 when considering a variety of American troops who deploy on temporary assignments that the Pentagon does not include in its official tally.

“We’re going to need airfield operations, and if you want to go in concentric circles around that we’re going to also have a logistics footprint there to facilitate the flow of goods and supplies and personnel through that airfield,” MacFarland said. “We’ll have a security envelope around that. We’ll have a communications capability there and a command-and-control or headquarters unit there, as well. There’s nothing really very sexy in any of that, but it’s all very necessary to keep the campaign moving forward.”

Carter, speaking before several dozen service members at Baghdad International Airport, said the additional troops will provide “critical enabler support to Iraqi forces at a key moment in the fight.”

The announcement came after Carter spent the day in Iraq meeting with U.S. military commanders and senior Iraqi officials. A small number of American troops arrived and carried out a “brief site survey” Sunday, said a senior U.S. military official, speaking on the condition of anonymity to discuss recent operations.

Carter told reporters traveling with him Sunday that the airfield seizure would create a “pincer” effect, placing Mosul between Iraqi security forces advancing from the south and Kurdish peshmerga forces maneuvering from the north. The United States already had established one staging base southeast of Mosul, in Makhmour, in March, but Qayyarah Air Base will provide another foothold, the Pentagon chief said.

U.S. Defense Secretary Ash Carter says the U.S. will set up a logistics hub to help Iraqi forces recapture Mosul from Islamic State. (Reuters)

The air base, about 20 miles west of the town of Qayyarah, is significantly larger than the base at Makhmour. Known to U.S. troops as Qayyarah Airfield West during the Iraq War, it includes at least one runway long enough to fly heavy cargo planes and room to fly numerous helicopters. It served as the site of a U.S. brigade headquarters known as Forward Operating Base Endurance during the last war.

One senior U.S. defense official traveling with Carter compared Qayyarah’s potential role to that of Taqqadum, a sprawling base in Anbar province where Marines and other Americans train Iraqis. It served a key role in the liberation of the cities of Ramadi in December and, more recently, Fallujah.

“We’ve got to get into Qayyarah. We’ve got to understand what’s there. We’ve got to have the Iraqis set up a perimeter,” the official said. “We’re just getting our feet on the ground there, but if Taqqadum is a nice example of what to compare it to, you can see a situation where weeks and months out, you are doing new missions and projecting from that location.”


A member of the Iraqi government forces inspects wreckage June 22 about 25 miles west of Qayyarah, during their operation to take the city and make it a launchpad for taking Mosul. (Mahmud Saleh/AFP via Getty Images)

There are other airfields in Mosul and Tal Afar, a city about 40 miles west of Mosul, but both are in Islamic State-held territory.

U.S. officials described the Iraqi advance that took back Qayyarah Air Base as the largest armored operation since Saddam Hussein’s forces invaded Kuwait in 1990. It included one battalion from the Iraqi army’s 9th Armored Division, three battalions from Iraq’s counterterrorism forces and the 92nd Brigade of the Iraqi army’s 15th Division, a senior Iraqi army commander said.

The commander, who spoke on the condition of anonymity because he said Prime Minister Haider al-Abadi’s office issued orders not to speak to the media, said the advance on the base began Saturday morning and that Iraqi forces controlled the installation by midday.

The commander said there was “not much” resistance from the Islamic State because of airstrikes from the U.S.-led coalition and fire support from U.S. rockets known as HIMARS, short for High Mobility Artillery Rocket System.

“Coalition forces destroyed everything, and then we advanced,” he said.

Lt. Gen. Abdel Ghani al-Asadi, commander of Iraq’s counterterrorism forces, said the Americans played a “significant role” in the battle. Some U.S. advisers based at Camp Speicher, about 100 miles south in Tikrit, left their base and drove to “secure areas” closer to the front lines in three or four vehicles in order to maintain better communications with Iraqi forces.

Asadi, who participated in the Kuwait invasion, said the armored component was “not at that level” but was the largest used in the fight against Islamic State. More than 50 tanks took part, he said. The armored component was more significant than in other operations because of the open geography of the area, he said.

Coalition airstrikes eliminated 60 Islamic State car bombs as Iraqi forces moved north from Baiji, “but they were all destroyed far away from our forces.”

“Now all Qayyarah Air Base is under our control, but there’s nothing left of it,” he said. He said that the militants, rather than coalition strikes, had destroyed the infrastructure of the base.

A brief video clip taken near the base and widely distributed on social media Sunday showed armored vehicles snaking through a desert as dark plumes of smoke rise in the background. It appears to have been taken from a helicopter. A U.S. military official in Baghdad confirmed Monday it is legitimate.

Brig. Gen. Yahya Rasoul, an Iraqi military spokesman, said military engineers will start rebuilding the airport in the next few days so that the base can accommodate Iraqi aircraft. He raised the possibility that coalition forces also could use it to launch airstrikes against targets in Mosul, although it was not clear that will be the case.

Abadi said in a tweet Saturday that he and “heroes” from the counterterrorism service called in a meeting for the people of Nineveh province to “prepare for liberation of their cities” after the securing of the air base.

U.S. officials raised the possibility ahead of Carter’s arrival Monday of American military advisers working alongside Iraqi troops at lower levels than they have been to prepare for operations in Mosul. Currently, they are approved to advise at the brigade and battalion levels, but have stayed at higher levels with more senior commanders serving at the division levels of leadership.

Carter did not rule out that MacFarland could temporarily base additional forces in Iraq that do not count against troop limits set in the United States — something that gained attention in March as the Marines set up a fire base southeast of Mosul at Makhmour. That was disclosed after a Marine in the unit, Staff Sgt. Louis Cardin, was killed by an Islamic State-fired rocket.

“There are and have always been people doing temporary things on temporary duty, deployed from other units,” Carter said. “General MacFarland had the authority to do those movements, and they’re routine and very varied, and the number goes up and down.”

Morris reported from Beirut. Mustafa Salim in Baghdad contributed to this report.