Iraqis push toward IS-held Mosul in long-awaited offensive

The long-awaited offensive to retake Mosul from the Islamic State group has begun with a volley of US-led coalition airstrikes and heavy artillery bombardments on a cluster of villages along the edge of Iraq's historic Nineveh plain east of the militant-held city.

Iraq's Kurdish peshmerga fighters led the initial assault yesterday, advancing slowly across open fields littered with booby-trapped explosives as plumes of black and orange smoke rose overhead - the opening phase of an unprecedented campaign expected to take weeks if not months, and involve more than 25,000 troops.

By the end of the day Kurdish forces had retaken some 200 square kilometres, according to the president of Iraq's Kurdistan region.

Peshmerga commanders on the ground estimated the offensive retook nine villages and pushed the frontline with IS back eight kilometres.

But the forces' hold appeared fragile and the gains largely symbolic. Some of the villages were so small they comprised no more than a few dozen homes, and most were abandoned.

And though some troops were less than 30 kilometres from Mosul's edges, it was unclear how long it would take to reach the city itself, where more than 1 million people still live. Aid groups have warned of a mass exodus of civilians that could overwhelm refugee camps.

Iraq's second-largest city, Mosul fell to IS in the summer of 2014 as the militants swept over much of the country's north and central areas. Weeks later the head of the extremist group, Abu Bakr al-Baghdadi, announced the formation of a self-styled caliphate in Iraq and Syria from the pulpit of a Mosul mosque.

If successful, the liberation of the city would be the biggest blow yet to the Islamic State group. After a string of victories by Iraqi ground forces over the past year, IS now controls less than half the territory it once held, and Iraqi Prime Minister Haider Al-Abadi has pledged the fight for Mosul will lead to the liberation of all Iraqi territory from the militants this year.

Al-Abadi announced the start of the operation on state television before dawn yesterday, launching the country's toughest battle since American troops withdrew from Iraq nearly five years ago.

In Washington, Defense Secretary Ash Carter called the Mosul operation "a decisive moment in the campaign" to defeat IS. The US is providing airstrikes, training and logistical support, but insists Iraqis are leading the campaign.

More than 25,000 Iraqi and Kurdish troops will be involved in the operation, launching assaults from five directions, according to Iraqi Brig. Gen. Haider Fadhil. The troops include elite Iraqi special forces who are expected to lead the charge into the city, as well as the Kurdish forces, Sunni tribal fighters, federal police and state-sanctioned Shiite militias.