Islamic State of Iraq and Syria (ISIS) insurgents took control on Thursday of large parts of the western Iraqi town of al-Baghdadi, threatening an air base where US Marines are training Iraqi troops, officials said.

Al-Baghdadi, about 85 kilometers (50 miles) northwest of Ramadi in Anbar province, has been besieged for months by the radical Islamist militants who captured vast swathes of northern and western Iraq last year.

Militants attacked al-Baghdadi from two directions earlier in the day and then advanced on the town, intelligence sources and officials in the Jazeera and Badiya operations commands said.

The officials said another group of insurgents then attacked the heavily-guarded Ain al-Asad air base five kilometers southwest of the town, but were unable to break into it.

About 320 US Marines are training members of the Iraqi 7th Division at the base, which has been struck by mortar fire on at least one previous occasion since December.

Pentagon spokeswoman Navy Commander Elissa Smith confirmed there was “heavy fighting” in al-Baghdadi. She said there had been no direct attack on the air base, but added: “There were reports of ineffective indirect fire in the vicinity of the base.”

An Iraqi defense ministry spokesman declined to comment on the situation in Anbar.

District manager Naji Arak confirmed that ISIS insurgents had entered al-Baghdadi and attacked some government buildings. He initially estimated the militants had taken 90 percent of the town but later said he could not confirm the extent of the group’s control as intermittent clashes continued into the early morning.

The death toll from the fighting was not immediately clear.

Elsewhere in Iraq, five civilians were killed when bombs went off in two towns south of Baghdad, police and medical sources said. Such attacks are not uncommon in and around the capital.

Most of the surrounding towns in Anbar fell under ISIS control following the group’s ground offensive in the country last summer that drove the Iraqi army — the recipient of $25 billion in US training and funding since the 2003 invasion — to collapse. The onslaught rapidly advanced across the Syrian border where captured territories in both countries were proclaimed part of the group’s caliphate.

The wide spread of ISIS control prompted the formation of a US-led coalition of around 60 mainly Western and Arab states that has been conducting a campaign of airstrikes against the jihadists in Iraq and Syria since August.

However, the effect of the open-ended US-led air campaign remains the subject of debate, with the White House saying the militants have been damaged by the strikes and critics pointing to ISIS’ advances and battlefield successes despite the raids.

Still, the US has been planning to stretch out its operations in targeting the militant group.

As Baghdad prepares for a major ground offensive expected within months, the US president said Wednesday that he consulted Republicans and Democrats in the US Congress before submitting a request for authorization of military force against ISIS.

Although the military operations stop short of a large scale invasion by US ground troops, Barack Obama claimed otherwise and said that the authorization could permit certain strikes involving US special forces and would be limited to three years to give his successor the opportunity to reevaluate the situation with Congress.

However, Iraqi Foreign Minister Ibrahim al-Jafaari said ground forces were not part of his government’s plan.

“We have established a set of guidelines,” for the international coalition, Jafaari told a press conference, stressing that this was to provide air support for Iraqi forces, training and intelligence.

(Reuters, Al-Akhbar)