But the PUK and KDP which have spent much of the past 11 years fighting among themselves for control of northern Iraq say they have united against this common enemy.
"[Ansar] al-Islam is a kind of Taliban," says PUK leader Jalal Talibani. "They are terrorists who have declared war against all Kurdish political parties. We gave them a chance to change their ways ... and end their terrorist acts. But if we can't do it through dialogue, we are obliged to use force."
Kurdish fighters, known as peshmerga, now patrol the road between Iraqi Kurdistan's southern city of Sulaymaniyah and Halabja.
On Sept. 23, Kurds here say, guerrillas ambushed a PUK unit and killed 42 soldiers. The ambush came after negotiations between the PUK and Ansar al-Islam, offering amnesty in return for peace, failed to end their activities.
Since the Sept. 23 ambush, peshmerga have pushed Ansar al-Islam back toward the Iranian border where they retain a stronghold in the town of Biara and surrounding villages.
"We have captured two of [Ansar's] bases and found the walls covered with poems and graffiti praising bin Laden and the Sept. 11 attacks on the US," says Mustapha Saed Qada, a PUK commander. "In one, there is a picture of the twin towers with a drawing of bin Laden standing on the top holding a Kalashnikov rifle in one hand and a knife in the other." He adds that the group has received $600,000 from the bin Laden network, and a delivery of weapons and Toyota landcruisers.
In an interview with the Kurdish newspaper Hawlati, the group's leader, Mala Kreker, declared bin Laden the "crown on the head of the Islamic nation."
Kurdish military sources say that Ansar al-Islam's Mr. Kreker is a former member of a Kurdish Islamic party who joined Ansar al-Islam after its formation in September. Kreker replaced Abu Abdullah Shafae an Iraqi Kurd who trained with Al Qaeda in Afghanistan for 10 years and changed his name from Warya Holery. Mr. Shafae is now Ansar al-Islam's deputy.