U.S. Marines' vehicles and equipment stand ready to be withdrawn from the Ein al-Asad airbase in Iraq’s Anbar province in December 2009. Five years later the Marines are back, this time to train Iraqi troops to take on ISIS. (AP Photo/Lara Jakes, File)

(CNSNews.com) – American troops training Iraqi recruits at a key airbase in Anbar province face “regular” but “completely ineffective” gunfire from Islamic State of Iraq and Syria (ISIS) fighters, according to the Pentagon.

They don’t shoot back, spokesman Army Col. Steve Warren said Monday.

Since last month some 320 U.S. troops have been training and advising Iraqi soldiers at the Ein al-Asad airbase about 100 miles north-west of Baghdad. Mostly U.S. Marines, they include advisors, support personnel and a security contingent.

Warren described the mortar and gunfire aimed at the sprawling base as “harassment” or “purely nuisance” attacks.

“American forces there right now have sustained absolutely no injuries, wounds or even equipment damage,” he said. “No U.S. personnel, no U.S. equipment has been impacted in any way.”

Warren said that, to his knowledge, there had been no contact between U.S. troops and ISIS fighters.

In mid-December some news reports citing Iraqi officials and local tribal figures claimed that U.S. troops at the airbase joined Iraqi troops in a gun battle that left an unknown number of ISIS fighters dead.

The incident – denied at the time by U.S. officials – purportedly took place on December 14. The only reports from U.S. Central Command of U.S. engagement in the vicinity over the Dec. 13-15 period spoke of ISIS vehicles being destroyed in an airstrike “near Hit.” The city of Hit is about 20 miles from the airbase.

Hit fell to ISIS in early October, and reports from Iraq in the following weeks said the Ein al-Asad base, the country’s third-largest military installation, was in danger of falling to the jihadists.

Fifty U.S. personnel arrived late that month, to lay the groundwork for the anti-ISIS training mission, and by December the number exceeded 300.

There are now more than 2,000 U.S. personnel in Iraq as part of Operation Inherent Resolve, the mission aimed ultimately at defeating the jihadist group that holds territory in Iraq and Syria. The U.S. is also carrying out airstrikes, along with various configurations of coalition partners, against ISIS targets in both countries.

In its most recent campaign update, on Monday, the operation’s Combined Joint Task Force reported that two airstrikes near Ein al-Asad on Sunday struck two ISIS tactical units and destroyed three vehicles.

The U.S. forces on the ground in Iraq are stationed in Baghdad, Taji near the capital, Erbil in the autonomous Kurdish zone, Ein al-Asad, and elsewhere.

In Taji, 170 U.S. Army personnel began training four battalions of vetted Iraqi forces on December 27.

Sunni tribal members during a validation ceremony for new “Popular Mobilization Program” recruits at the Ein al-Asad airbase in Anbar province on Jan. 1, 2015. (Photo: Combined Joint Task Force, Operation Inherent Resolve)

Kurdish peshmerga fighters are being trained in the north, and a second batch of several hundred Sunni tribesmen are now under training at Ein al-Asad. They are part of what is called the “Popular Mobilization Program” aimed at drawing members of Iraq’s often disaffected Sunni minority into the battle against the Sunni jihadists of ISIS.

Heading towards 3,000

In line with an announcement by President Obama last November, the number of U.S. troops now on the ground in Iraq – trainers, advisors and force protection personnel – will grow by another 1,300 or so in the coming weeks, bringing the total to more than 3,000.

The deployment began with an announcement by Obama last June that he was sending “up to 300” advisors to Iraq to assess how the U.S. can advise and support Iraqis in their fight against ISIS.

In a speech in September the president reiterated that the U.S. personnel going to Iraq would have no combat role.

“The American forces that have been deployed to Iraq do not and will not have a combat mission. They will support Iraqi forces on the ground as they fight for their own country against these terrorists,” he told troops at the MacDill Air Force Base in Tampa, Florida.

“As your commander-in-chief, I will not commit you and the rest of our armed forces to fighting another ground war in Iraq. After a decade of massive ground deployments, it is more effective to use our unique capabilities in support of partners on the ground so they can secure their own countries’ futures.”

Two months later, chairman of the Joint Chiefs of Staff Army Gen. Martin Dempsey told the House Armed Services Committee that while he was not predicting he would recommend that U.S. forces accompany Iraqi troops as they try to retake Mosul or territory along the Iraq-Syria border from ISIS, “we’re certainly considering it.”

ISIS captured Mosul, Iraq’s second-biggest city, last June.