It has been over three years since the war on the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) was announced. The US-led offensive has changed realities on the ground, altering the trajectory of the civil war in Syria and shifting the balance of power in Iraq.

After the Islamic State of Iraq, an offshoot of al-Qaeda, announced its extension into the Levant in March 2013, the group swiftly expanded its territory in eastern Syria. In early 2014 it took over the Syrian city of Raqqa, which was made into its capital, and a few months later conquered the Iraqi city of Mosul, where its leader Abu Bakr al-Baghdadi declared a caliphate in June 2014. Within a year, ISIL took control of most of eastern Syria and about one-third of Iraq's territory.

The unexpectedly rapid expansion of ISIL and the massive influx of foreign fighters to its ranks came as a shock to Western and regional powers. In September 2014, the US announced the formation of an international coalition to fight ISIL and as of February 2017, the Pentagon says it has spent almost $12bn on the anti-ISIL operation.

In Syria, the United States gradually shifted its priorities - and by association that of its allies - away from toppling Bashar al-Assad and towards defeating ISIL. It has funded the Kurdish People's Protection Units (YPG) and its umbrella group the Syrian Democratic Forces (SDF) in its fight against ISIL in northern Syria and has encouraged various Syrian opposition groups to focus on ISIL as well. Although Russia has not been part of the anti-ISIL coalition, after its military intervention in Syria, it established a certain degree of coordination with the US.

In Iraq, following the collapse of the Iraqi army in the face of the advancing ISIL forces, the US chose to back Kurdish forces with funding, training and weapons. It has also come to tolerate the involvement of Iran-backed militias in the fight against ISIL.

So far the US-coalition has managed to push ISIL out of most of Iraq and it is currently escalating its offensive in Syria. With ISIL defeated in the Iraqi city of Mosul and the battle for Raqqa raging on, ISIL is losing control over major urban centres. Analysts say that as the armed group loses more territory, it will revert to a guerilla-style insurgency in the countryside of Iraq and Syria.