NAYMIYAH, Iraq — After securing the southern edge of militant-held Fallujah, seven battalions of Iraqi special forces units have been unable to advance for two days – a delay that commanders say isn’t due to counterattacks or difficult terrain, but rather to disagreements about battlefield strategy among the disparate Iraqi forces fighting the Islamic State group, also known as ISIS.

Unlike previous anti-ISIS operations, the fight for Fallujah involves an array of Iraqi security forces. A battle plan that was initially cast as an example of how those fighters can work together has instead revealed just how fractured Iraq’s security forces are.

“I wouldn’t say the different forces in the Fallujah operation are cooperating: They’ve just divided up the battlefield,” said Patrick Martin, an Iraq analyst with the Institute for the Study of War, a think tank based in Washington.

Since ISIS overran Mosul in the summer of 2014, two groups have come to dominate the fight against the militant group in Iraq: The country’s elite counterterrorism special forces and the government-sanctioned, largely Shiite militias known as the Popular Mobilization Forces.

Maj. Ahmed Na’im with the Anbar province police force says while his men and the Iraqi federal police are fighting the same enemy in the same city, they never coordinate operations or share intelligence.

“They have their own plans and take their orders from their own people,” he said.

Two days after taking up positions on the outskirts of Fallujah, one such dispute brought operations to a halt on Tuesday.