Defeated Islamic State fighters from the Iraqi city of Mosul are likely to enter Europe to carry out terrorist attacks, the European Union's (EU) security chief has warned. Thousands of Europeans who left to fight for ISIS in Iraq and Syria over the past few years may have already begun returning to the continent after the terrorist group suffered a string of territorial defeats in the Middle East, warned Julian King, theEU's Commissioner for Security. "The retaking of Islamic State's northern Iraq stronghold, Mosul, may lead to the return to Europe of violent ISIS fighters," King told the German newspaper'Die Welt'. According to King, a British diplomat who recently took charge as security commissioner, even a handful of such terrorists returning would pose a serious threat. French defence minister Jean-Yves Le Drian has warned the fight to liberate Mosul in its entirety could take a long time. "It's not a blitzkrieg.
It's a city with 1.5 million residents, so it's a long-term project - several weeks, maybe months," he said. Some 34,000 Iraqi security personnel, Kurdish fighters, Sunni Muslim Arab tribesmen and Shia Muslim paramilitaries have been deployed against ISIS, with backing from the US, France and others. Their advance on Mosul comes over two years after the city was seized by ISIS in a major coup that enabled the extremist group to announce a self-proclaimed caliphate spanning Iraq and Syria. Iraqi forces say they have captured 10 villages near Mosul since beginning their long-awaited offensive on Monday. As many as 5,000 ISIS fighters are believed to remain in the city. If the city is reclaimed by the Iraqi government, ISIS will be left with the Syrian city of Raqqa as its last major stronghold.