Tanks, armored vehicles and heavy weapons of the Islamic State group have gathered near a rural town just 25 miles (40 km) west of Baghdad, Amariyah al-Falluja, apparently poised for a major attack. The group also known as ISIS, which is said to be surrounding the town on three sides, has been conquering large chunks of Anbar province in recent weeks, while being stopped in its push toward Baghdad and resorting to terror tactics such as suicide attacks.

Should the Sunni militants take Amariyah, it would represent the biggest coup for the group since it took Al-Mada’in, which is just 12 miles (20 km)  south of Baghdad, earlier this year. Controlling the area would give ISIS a transportation corridor that follows the Euphrates River and links two of its strongholds, the city of Fallujah and a region in northern Babil province, south of Baghdad. 

“The situation is dangerous here,” Sheikh Faisal al-Esawi, a local official and leader of the Albu Esa, Sunni tribe opposed to ISIS, told the New York Times. According to officials on the ground, no shots had yet been fired on Thursday morning. ISIS has already managed to rout police and army units from about 80 percent of Anbar, a vast western province.

More than just strategic territory, Iraq’s largest province by area was the breeding ground for the Sunni insurgency against U.S. forces that followed the Iraq invasion in 2003. However, by 2006 the Sunni tribes decided to back the U.S.-supported government against al-Qaeda affiliates in the country.

Now the province is in a fluid state where alliances are largely unclear. The sectarian policies of former Prime Minister Nouri al-Maliki, a Shia, alienated the Sunnis in the region, which has, according to a Washington Post report from early October, fueled support for the jihadist cause and aided ISIS in its surge across Anbar. But al-Maliki left office in September, and the Anbar Tribal Council once again put its backing behind the government's fight against ISIS. Still, the council “will not confront the Islamic State while Shiite militias exist in Sunni areas,” tribal chief Samil al-Muhammadi told the Saudi-owned London newspaper Al-Hayat.

The town of Amariyah al-Fallujah has dealt with two raids from the Islamic State group over the last month, but Iraqi army and police, in alliance with the Albu Esa tribe, managed to push them back.