Kurdish forces entered parts of Sinjar on Friday morning after cutting off the main Highway 47 to the east and west.

Nearly 7,500 Iraqi Kurdish peshmerga alongside Yazidi units and the PKK launched a long-planned offensive on the northern Iraqi town of Sinjar and surrounding territory early on Thursday morning, in what forces fighting the "Islamic State" (IS) hope will deal a severe blow to the organization.

By controlling Highway 47, Kurdish forces have cut off the main supply route that connects IS-controlled Mosul, Iraq's second largest city, to its de facto capital in Raqqa, Syria.

Up to 800 IS militants are estimated to be holed up in Sinjar, but Kurdish officials said some had fled overnight as Kurdish forces pounded the town and called in US airstrikes on IS positions. US advisors are coordinating with Kurdish forces who are calling in the airstrikes from Mount Sinjar overlooking the city.

It could take several days to secure the town and up to another week to conduct clearing operations, a US official said.

Symbolic and Strategic

Retaking Sinjar would be a symbolic victory for the Kurds and the coalition. IS took the town last year after peshmerga forces tied to Iraqi Kurdistan's President Masoud Barzani's KDP collapsed. The capitulation left the minority Kurdish Yezidis, who follow a syncretic religion deemed heretical to hard-line Islamists, open to slaughter and other atrocities.

Thousands of Yazidis were forced to flee, hundreds were killed, and Yazidi girls and women were enslaved. The plight of the Yezidis brought the barbarity of IS to international attention.

A wider-scale slaughter was prevented by the US-led air campaign, and forces tied to Turkey's banned Kurdistan Workers' Party (PKK) and its Syrian affiliate, the People's Protection Units (YPG).

The collapse of KDP forces opened deep divisions between the main Iraqi Kurdish party and Yazidis, some of whom were later trained to defend themselves by the PKK and are now participating in the Sinjar offensive. The Iraqi Kurdish peshmerga also trained Yezidi units.

The Sinjar offensive comes as PKK-affiliated forces in Syria, the YPG, and Arab militias are planning an assault on Raqqa, backed by US special forces and air power. Retaking Sinjar would hinder IS's ability to move forces and equipment between Iraq and Syria ahead of an assault on the de facto IS capital.

cw/rc (AP, Reuters)