ISIS attacked the Sinjar area in August, sending thousands of Yazidis fleeing up the mountain, a craggy strip some 40 miles long.
Hundreds of Yazidis were executed by ISIS. A senior U.N. rights official said the onslaught looked like "attempted genocide".

Kurdish peshmerga forces have regained between 65 and 75 percent of the ground lost to ISIS in the area since the U.S. began a campaign of air strikes in August, said Halgurd Hikmat, spokesman for the Kurdish Peshmerga Ministry.

But Sinjar's awkward geography -- out on a limb to the west, has made it difficult to penetrate.

"Our priority now is Sinjar," said Hikmat. "A plan will be in place within the coming days.”The strategy was to cut off an ISIS supply route between Mosul and Syria which runs along the southern foot of the mountain, Hikmat said.

Controlling Sinjar would put the peshmerga on three sides of Mosul, the largest city under ISIS control in northern Iraq, and allow them to gain positions for any future offensive to retake the city and nearby areas which have been the target of Iraqi and U.S. air strikes.

"After that, we must coordinate with Baghdad and the coalition (of Western and Gulf Arab states) to get ISIS out of Mosul," said Hikmat.

Mosul has become the focus of the government's military efforts because of both its size and its symbolic status after ISIS leader Abu Bakr al-Baghdadi delivered a public speech at the Grand Mosque there in July.

An Iraqi Yazidi boy poses under a bridge where displaced people of this religious minority found refuge after ISIS militants attacked the town of Sinjar on August 17, 2014 on the outskirts of the Kurdish city of Dohuk, in Iraq's autonomous Kurdistan region.

STRANDED

Estimates of the number of people still stranded on Sinjar Mountain vary from 10,000 to fewer than 1,000.

Last month, the peshmerga recaptured the town of Rabia, taking control of a crossing point into Syria and moving closer to Sinjar.

Further advances may not come easily. An intelligence officer in the Rabia area said it would take between two to three weeks to drive ISIS out of the villages north of Sinjar Mountain, because some Arab residents either supported ISIS, or opposed Kurdish encroachment.

A Yazidi fighter told Reuters by telephone from the mountain that he was one of around 1,500 volunteers there, in addition to a contingent of around 150 peshmerga.

Hikmat put the number of peshmerga at 2,000. "We have received several (types of) small arms from the Kurds, including AK-47s, sniper rifles, mortars and light machine guns," said the volunteer fighter, who gave his name as Barakat.

Politically, Sinjar has been damaging for the Kurdistan Democratic Party (KDP) -- one of two main Kurdish power centres -- whose forces were responsible for protecting the area.

Since 2003, the KDP has courted and co-opted minorities in the disputed areas along its southern border by providing them with jobs, security and services in exchange for loyalty.

Displaced Iraqi families from the Yazidi community cross the Iraqi-Syrian border at the Fishkhabur crossing, in northern Iraq, on August 11, 2014. At least 20,000 civilians, most of whom are from the Yazidi community, who had been besieged by terrorists on a mountain in northern Iraq have safely escaped to Syria and been escorted by Kurdish forces back into Iraq, officials said.

"The KDP and the Yazidis are inseparable parts of the same body, and that also applies to the KDP and Sinjar," Barzani, who is also head of the KDP as well as commander-in-chief of the peshmerga, told Yazidi members of his last month.

Rival parties have capitalised on the loss of Sinjar to score political points against the KDP.

The Syrian Kurdish YPG militia, which crossed into Iraq and saved thousands of Yazidis over the summer has won favour with the minority, many of whom felt betrayed by the peshmerga.

Thousands of Yazidis have since been trained by the YPG in Syria, and a small number of guerrillas remain on the mountain, according to fighters there.

Peshmerga spokesman Hikmat said the YPG would not participate in the Sinjar offensive, but that the peshmerga would coordinate with them to protect the area afterwards.