Baghdad - Iraq brought all of its territory still held by Islamic State attack on Thursday, throwing the jihadists on the defensive across their self-proclaimed "caliphate" extending into neighbouring Syria.Security forces backed by paramilitary units launched a dawn assault on a besieged ISIS-held pocket around the northern town of Hawija, just days after attacking the jihadists' only other foothold in the country.The territory still held by ISIS has been dwindling fast since its defeat in Iraq's second city Mosul in July, with stronghold after stronghold coming under assault on both sides of the border with Syria.Most of its onetime Syria bastion Raqa, long a byword for its most gruesome atrocities, is now in the hands of US-backed fighters, while elsewhere in Syria ISIS has suffered major losses to Russian-backed government forces.Iraqi Prime Minister Haider al-Abadi predicted that the assault on the Hawija region would swiftly bring a new victory against the crumbling jihadists.The mainly Sunni Arab enclave, which was bypassed by government forces in their advance north to Mosul last year, has been a bastion of insurgency ever since the first year of the US-led occupation in 2003.After the defeat of ISIS in Mosul and the recapture of adjacent areas, Hawija and neighbouring towns form the last enclave still held by ISIS in Iraq apart from a section of the Euphrates Valley downstream from the border with Syria.'Victory after victory' "At the dawn of a new day, we announce the launch of the first stage of the liberation of Hawija, in accordance with our commitment to our people to liberate all Iraqi territory and eradicate Daesh's terrorist groups," Abadi said, using an Arabic acronym for IS."Greetings to all of our forces, who are waging several battles of liberation at the same time and who are winning victory after victory and this will be another, with the help of God," he said.An AFP correspondent heard heavy shelling around the ISIS-held town of Sharqat where Iraqi forces have been massing in recent days.The US-led coalition fighting ISIS hailed the new offensive by the Iraqi security forces (ISF) against the jihadist group."#ISF launch Hawija operations to #defeatDaesh. #ISIS now faces the mighty #ISF the last two areas where they hold any territory in #Iraq," a spokesperson tweeted.#ISF launch Hawija operations to #defeatDaesh. #ISIS now faces the mighty #ISF the last two areas where they hold any territory in #Iraq.— OIR Spokesman (@OIRSpox) September 21, 2017 Hawija earned the nickname of "Kandahar in Iraq" from coalition troops from the early months after the invasion of 2003 for the ferocious resistance it put up similar to that in the Taliban militia's bastion in Afghanistan.Located west of the ethnically divided Kurdish-held city of Kirkuk, Hawija also lies on a fault line of Arab-Kurdish tensions.Despite forming part of Kirkuk province, the area is overwhelmingly Sunni Arab and bitterly opposed to Kurdish ambitions to incorporate Kirkuk in their autonomous region in the north.Preparations for the offensive in Hawija have been overshadowed by an independence referendum that Kurdish leaders plan to hold on Monday in areas including Kirkuk against the wishes of the federal government in Baghdad.TerritoryIt is the latest in a string of setbacks for ISIS in Syria and neighbouring Iraq.After seizing swathes of the two countries in 2014, ISIS has seen the territory under its control fast diminish in recent months.On Tuesday, Iraqi forces launched an attack up the Euphrates Valley against the other one of IS's two remaining enclaves in Iraq.And in Syria's eastern province of Deir Ezzor, ISIS faces twin assaults - one by Russian-backed government troops and the other by US-backed fighters of the Syrian Democratic Forces.Further up the Euphrates, the SDF now controls 90% of the city of Raqa, the Britain-based Syrian Observatory for Human Rights war monitor said on Wednesday.The US-led coalition supporting the SDF estimated that 65-70% of Raqa is now under the control of the alliance of Kurdish and Arab fighters.The jihadists seized Raqa in early 2014, making it their de facto Syria capital. They are thought to have used the city to plan attacks abroad.ISIS also holds pockets of territory elsewhere in Syria, notably in eastern parts of the central provinces of Homs and Hama, but it is the target of attack by Russian-backed government forces there too.