Marines at a forward training base for the Iraqi security forces in western Anbar province have come under "regular" but spotty indirect fire in recent weeks from ISIS, mostly from mortars, the Pentagon said Monday.

"It's fair to say the al-Asad command has come under regular fire" but "the fire has been completely ineffective. These are purely nuisance attacks," Army Col. Steve Warren, a Pentagon spokesman, said of the sprawling outpost of the Iraqi army at the former al-Asad airbase west of Baghdad.

U.S. troops, who have been barred from ground combat by President Obama, have not returned fire and left the Iraqi national security forces to deal with the indirect fire threat from the Islamic State of Iraq and Syria (ISIS).

Warren said no U.S. personnel or equipment have been hit by the ISIS fire.

"The Iraqi security forces there have done a very good job of creating a security zone," Warren said.

About 320 Marines from a Marine Air Ground Task Force (MAGTF) assigned to the U.S. Central Command were at al-Asad on an advise and assist mission to the Iraqi forces that has accelerated in recent weeks. The Marines began training units from Iraq's 7th Division on Dec. 20, Warren said.

The Army's 1st Infantry Division was engaged in a similar mission at an Iraqi base near Taji north of Baghdad. On Dec. 27, about 170 1st Infantry troops began what was essentially a 6-week boot camp for Iraqi recruits with the goal of forming several battalions of new troops, Warren said.

Currently, there are about 2,140 U.S. troops in Iraqi. About 800 of those troops are engaged in providing security and force protection, and the remainder are training, advising and assisting the ISF and Peshmerga. Obama has authorized the deployment of an additional 1,000 U.S. troops.

The U.S. plans to set up at least two more training facilities – one in northern Irbil, capital of the Kurdish region, and at Besmaya about 55 miles southeast of Baghdad.

President Obama has authorized the deployment of about 1,000 more U.S. troops to Iraq, most of them from the 82nd Airborne Division based at Fort Bragg, North Carolina.

The U.S. has put a premium on training Iraqi troops to go on the offensive this year against ISIS, which has taken large chunks of territory in northern and western Iraq.

Meanwhile, U.S. and coalition warplanes continued nearly daily airstrikes against ISIS targets in Iraq and Syria. In a Jan. 5 release, CentCom said that a total of 20 airstrikes were carried out in the Jan. 4-5 period – 14 in Syria and six in Iraq.

The U.S. and its coalition partners have now conducted a total of 50 airstrikes in 2015 – 32 in Syria and 18 in Iraq, according to CentCom reports. Last year, CentCom reported a total of 1,565 airstrikes from Aug. 8, when Obama authorized the air campaign, through the end of the year.

-- Richard Sisk can be reached at richard.sisk@military.com