The PUK has mobilised around 5,000 fighters for a ground assault
As the US-led coalition forces press in towards Baghdad, another confrontation appears to be imminent in the remote hills and mountains of north-east Iraq, close to the border with Iran.
It would pit thousands of Kurdish pesh merga guerrillas - with the support of US air power and some special forces - against an estimated 800 fighters from the radical Ansar al-Islam faction.
The Ansar al-Islam control a belt of rugged territory north of Halabja, including some 40 villages, stretching up to the Iranian border which runs along the mountain ridge to the east.
Both Washington and the Patriotic Union of Kurdistan (PUK), the Kurdish faction which controls much of the surrounding area, regard the Ansar al-Islam as terrorists linked to Osama Bin Laden's al-Qaeda movement.
'Nothing but trouble'
The US - which justified its intervention in Iraq by the need to root out "terrorism" - seems to have set the elimination of Ansar al-Islam as one of its opening objectives.
We are looking to the Americans for air support, missile strikes, special forces
PUK leader Jalal Talabani
A massive US missile strike was carried out on the area on Friday night, followed by bombing raids later.
The strikes were seen as preparation for a ground assault which is expected to get under way in the next few days.
"We hope it will all be over within about four days," said a pesh merga commander on a hilltop position commanding a panoramic view of the enclave held by the Ansar al-Islam.
"The Ansar are terrorists who have caused nothing but trouble."
Little is known about how much damage the US bombardments have done.
Islamic group hit
Ansar al-Islam's fighters are spread through a large area. They were well aware that they were targeted, so it is thought likely that they would have abandoned the most obvious installations and dispersed into the hills long before the strikes began.
The first missile attack caused heavy casualties, but not among the Ansar.
A military centre belonging to another Islamic group, the Komola, was devastated, and nearly 60 people killed.
The Komola control an area to the west of the Ansar pocket, and overlap both geographically and ideologically with the group.
The PUK had repeatedly warned them to take their distance from the Ansar, but they apparently disregarded the advice.
The PUK has mobilised an estimated 5,000 fighters for an impending ground assault.
On Saturday night, PUK officials reported that US special forces began arriving through an airstrip close to Sulaymanieh, though their movements were shrouded with secrecy.
Roads to Halabja were barred to journalists for two days, creating speculation that the special forces were being transported discreetly eastwards of the Ansar enclave in readiness to join operations alongside the PUK's pesh merga.
Kurdish leaders have no qualms about seeking US help to wipe out the Ansar.
"We are looking to the Americans for air support, missile strikes, special forces - everything that might help to eradicate this terrorist group," said Jalal Talabani, leader of the PUK.
The Ansar are certainly no angels.
Their bloodiest action came in 2001, when they overran the village of Kheli Hama and butchered 42 captured pesh merga guerrillas from the PUK, some of them killed with hands tied behind their backs.
The Ansar are also blamed for a string of assassination attempts and other outrages, including, most recently, a suicide car bomb attack at a PUK checkpoint on Saturday in which an Australian cameraman was among five people killed.
Because of their proximity to the Iranian border, the operation to eradicate the Ansar will be a delicate affair.
Iran is known to be extremely sensitive about any US action close to the frontier.
Tehran distanced itself from the Ansar last year by expelling its alleged leader, Najm Faraj Ahmad, known as Mullah Krekar, who had been detained at Tehran airport.
Krekar was arrested in Norway last week and charged with planning terrorist acts.