The Iraqi-led military offensive to recapture the city of Mosul from the Islamic State could trigger a return of jihadists to European Union member states, the EU security union commissioner warned on Tuesday.
Julian King told the German newspaper Die Welt that even a small number of militants crossing into Europe would pose "a serious threat that we must prepare ourselves for," the BBC reported.
Still, he emphasized that it is "very unlikely that there would be a mass exodus of ISIS fighters to Europe."
The Iraqi army launched its operation to retake the ISIS stronghold on Monday. The U.S. expects ISIS will suffer a "lasting defeat" should Mosul, Iraq’s second largest city, fall to Iraqi and Kurdish troops.
King estimated there are currently 2,500 fighters from EU countries in the combat zones. Some 5,000 ISIS fighters are thought to still remain in Mosul.
Pentagon spokesman Peter Cook said Monday the operation was "ahead of schedule," but heeded that it remains unclear whether ISIS would "stand and fight" once troops reach the city.
The operation is expected to take weeks, even months.