ALEPPO, Syria — The spectacular and shocking offensive in Iraq by the Islamic State of Iraq and al-Sham (ISIS) that has seen the extremist terror group take large areas in the west of the country, including its second largest city, Mosul, has the entire region and the world rightly worried. ISIS is said to boast an army of 10,000 fierce fighters, more than $2 billion in assets and huge caches of weapons and equipment seized from the Iraqi army, making it a serious threat to global security. The ISIS resurgence in Iraq feeds off the group's escapades in Syria, where it developed from welcomed liberator to despised villain. Will history repeat itself in Iraq?

Abu Jimaa is a middle-aged man with a large family who hails from the town of Bayanoun, a town in Aleppo’s north countryside well-known for its religious conservatism and as the birthplace of many of the leaders of the Muslim Brotherhood in Syria from the al-Bayanouni family. When the Syrian conflict escalated and became armed, Abu Jimaa took up weapons along with many of his townsfolk and joined a local rebel militia. In January, he was involved in routing ISIS from Bayanoun, after their successful advance into the northern countryside, starting with the border town of Azaz, near the Turkish border.

Back then, Abu Jimaa told me how they felt betrayed by the group they had once worked with and welcomed, believing they were liberators who shared their vision and ambition to topple Syrian President Bashar al-Assad’s regime. “We didn’t mind that there were many foreigners among them. In fact, we thought it was a great sacrifice and an honor that they would leave their own countries and risk their lives fighting for us. We thought they were our friends and brothers,” Abu Jimaa said at the time.

That special friendship peaked in summer 2013 after ISIS, led by Abu Omar al-Shishani, took the Minnigh military airport, north of Aleppo, after a 10-month siege, prompting the then-head of Aleppo’s Free Syrian Army military council, Col. Abdul Jabbar al-Oqaidi, to sing its praises. That did not last for long, however. After the initial euphoria, it became apparent that ISIS had other plans. Far from sharing the rebels’ goal of ridding Syria of the Assad clan, ISIS' priority was establishing an extremist Islamist caliphate on territory the regime no longer controlled.