ISIS greatest global threat: US report

The ISIS terror group remained the greatest threat globally in 2015, maintaining a formidable force in Iraq and Syria, including a large number of foreign terrorist fighters, a US report said on Friday.

ISIS' capacity and territorial control in Iraq and Syria reached a high point in spring 2015, but began to erode over the second half of 2015, the State Department said in its annual Country Reports on Terrorism 2015.

"IS did not have a significant battlefield victory in Iraq and Syria after May. At the end of 2015, 40 per cent of the territory IS controlled at the beginning of the year had been liberated," it said in its annual Congress-mandated report.

In Syria, local forces expelled ISIS fighters from several key cities along the routes connecting the two ISIS strongholds of Raqqa and Mosul, and reclaimed about 11 per cent of the territory ISIS once controlled.

These losses demonstrated the power of coordinated government action to mobilize against and confront terrorism, it said.

Despite this, ISIS "remained the greatest threat globally, maintaining a formidable force in Iraq and Syria, including a large number of foreign terrorist fighters," it said.

Noting that ISIS' loss of territory in Iraq and Syria in 2015 diminished its availability of fund, the State Department said the terrorist organization relied heavily on extortion and the levying of "taxes" on local populations under its control, as well as a range of other sources, such as oil smuggling, kidnapping for ransom, looting, antiquities theft and smuggling, foreign donations, and human trafficking.

Coalition air strikes targeted ISIS' energy infrastructure - modular refineries, petroleum storage tanks, and crude oil collection points - as well as bulk cash storage sites.

"These airstrikes have significantly degraded IS' ability to generate revenue. The United States led the international effort, including through the UN, to confront IS' oil smuggling and its antiquities dealing, delivering additional blows to its financial infrastructure," it said.

Along with ISIS, al-Qaeda and both groups' branches increased their focus on staging mass-casualty attacks including attacks on international hotel chains in Burkina Faso, Mali, and Tunisia; other popular public locations; and the bombing of a Russian passenger plane, it added.

While ISIS lost significant territory in Iraq and Syria during the second half of 2015, the group made gains in Libya amid the instability there.

And in January, ISIS publicly announced the establishment of an affiliate, known as ISIL-Khorasan (ISIL-K), in Afghanistan and Pakistan, it said.

"At year's end, the group had focused the majority of its attacks against Afghan government and civilian targets, although the group has also claimed a small number of attacks in Pakistan's settled areas."

"ISIL-K gained a small foothold in southern Nangarhar province in Afghanistan, but was significantly challenged by the Afghan government, Coalition Forces, and the Taliban, and had little support among the region's population," the State Department said.