IS kill scores of US-backed fighters in eastern Syria
The Islamic State group launched a counter-attack on a Kurdish-led force in eastern Syria, a monitor said on Tuesday, as bad weather stalls an offensive against the jihadis.
The IS assault killed 23 members of the US-backed Syrian Democratic Forces (SDF) with nine IS militants also killed in the battle.
Storms have allowed IS to launch a number of offensives against the SDF in recent weeks in the Euphrates Valley, which have included the use of suicide bombers.
Bad weather has canceled out the SDF advantage of US-led coalition air support, while sand storms have given IS fighters cover during counter-attacks.
"Twenty-three SDF fighters were killed and nine IS jihadists were also killed in fighting that lasted all night and into Monday morning," Observatory chief Rami Abdel Rahman said.
After capturing huge swathes of Syria and Iraq in 2014, IS are now confined to a small territory along the Euphrates River.
An Iraqi government and Kurdish offensive in Iraq has seen IS defeated there. A US-backed, Kurdish-Arab assault in Syria has seen the group's territories whittled down to a small clutch of villages in the east of the country.
The SDF launched a final offensive on the group four months ago with US-led coalition air support.
IS have managed to launch rocket and bomb attacks on Kurdish forces including one blast at a centre on Monday.
The attack comes as the US is sending mixed signals over its long-term commitment to the fight against IS in Syria, following Donald Trump's shock announcement of withdrawal from the country.
US President Donald Trump has gone back on a previous promise to swiftly pull-out from Syria saying the withdrawal would be done in a "prudent" manner.
Trump said the fight against the Islamic State group will continue until they have been defeated.
"We will be leaving at a proper pace while at the same time continuing to fight ISIS and doing all else that is prudent and necessary!" Trump tweeted, using an acronym for the Islamic State.
This follows the announcement in late December that American troops would be withdrawn from Syria immediately.