'Weakening Syria's govt could help IS'

The Islamic State group could inadvertently benefit from a situation in which Syrian government forces are considerably weakened on the ground, a London-based military analysis group has said.

The report, published by IHS Jane's Terrorism and Insurgency Centre, follows the United States bombing of a Syrian army base after a chemical weapons attack on April 4 killed nearly 90 people.

The US has accused the Syrian government of being behind the attack charges that Syria denies.

In Syria, the Islamic State group is battling both government forces and forces allied with the US-led coalition. If Syrian government forces are weakened, IS fighters could more easily move into heavily populated cities and towns, said Columb Strack, senior Middle East analyst at IHS Markit. "The Syrian government is essentially the anvil to the US-led coalition's hammer," Strack said. Weakened Syrian government forces could give the militants additional footholds at a time when their grip on territory elsewhere in Syria and Iraq is being rolled back, Strack explained.

In Iraq, IS has lost more than half the territory the militants once controlled there and is now fighting to defend a cluster of western Mosul neighbourhoods that mark the last significant urban area the group holds in that country.

Across both Iraq and Syria, IS has lost nearly half the territory it held at the height of its power in 2014. Since then, a combination of more intense US-led coalition involvement in the fight against IS and Syrian government advances in Aleppo and Palmyra have pushed IS out of more than 40,000sqkm of territory.