(CNN) -- A key province near Iraq's capital is in trouble amid an onslaught from ISIS forces, the U.S. defense secretary said Friday, signaling the Islamist extremist group is continuing to flex its muscles and expand its territory -- on several fronts -- despite international airstrikes.
Speaking to reporters during his travels in South America, U.S. Defense Secretary Chuck Hagel said there's a lot of uncertainty about what will happen with Anbar province, which is just west of Baghdad.
These comments are in alignment with those of a senior U.S. defense official who told CNN that Iraqi forces are "up against the wall" in Anbar. Some units are in danger of being cut off by the advancing militants, who call themselves members of the Islamic State.
The Iraqis' ultimate goal is to take back some of the vast areas, in both Iraq and Syria, that ISIS controls. But right now, Iraqi forces appear to be mostly trying to survive -- taking defensive positions and using Apache helicopters again, even after two were shot down in the area this week, according to the U.S. official.
"We do see ISIL continue to make gains in Anbar province and (are) mindful of how Anbar relates to the security of Baghdad," said another senior U.S. defense official.
The first official said the U.S. military is more confident right now about the Iraqi military's ability to protect Baghdad. The Iraqi brigades defending the capital are more capable and include U.S. military advisers, so at least Washington should have a better sense there if there's any imminent danger.
Abu Ahmed, a 42-year-old colonel who belongs to a group allied with the Iraqi government, said that "a large number of ISIS militants" attacked al-Garma, in Anbar province, around 3 a.m. Friday.
What began with the detonation of seven vehicles by a bridge ended about five hours later. In between, Ahmed said there was "a fierce battle" with ISIS militants on one side and Iraqi and local allied forces on the other.
"During the fight, ISIS militants set some oil containers and tires on fire to block the view from the Iraqi air support that was called in," Ahmed said. "... The Iraqi army and Awakening Council fighters did not advance to the positions where ISIS militants were fighting, fearing booby traps and planted (improvised explosive devices)."
This is not the only place where ISIS forces are fighting.
About 800 kilometers (500 miles) from Baghdad, the Islamist extremist group continued to inch forward in the Syrian city of Kobani.
The Kurdish enclave has been a hotspot for days, largely due to its location a stone's throw from the Turkish border. Emotional and, at times, violent protests have broken out in Turkey among people calling for ground forces to intervene -- something Foreign Minister Mevlut Cavusoglu said Thursday won't happen, so long as Turkey has to go it alone.
ISIS fighters controlled about half of the Syrian city on Friday, significantly more than even a day earlier, after taking over Kurdish administration buildings in what had been a security zone, the Syrian Observatory for Human Rights reports.
The United States has launched multiple airstrikes to try to curb the ISIS advance, including two Friday that the U.S. military says destroyed some of the group's infrastructure and vehicles.
But such efforts haven't prevented ISIS fighters from restocking with munitions from the Syrian cities of Aleppo and Raqqa, according to the observatory, a London-based monitoring group.
Nor have they stopped fresh fighters from arriving in Kobani, which is also known as Ayn al-Arab.
CNN's Kareem Khadder, Hamdi Alkhshali and Juan Carlos Lopez contributed to this report.