US-backed forces relaunch battle against IS in Syria
The US-backed fighters had paused the battle after Turkey launched an offensive in January against the Kurdish Afrin region in northwestern Syria.
Ahmed Abu Khawla, commander of the Deir az-Zour military council fighting under the SDF, said they were working with the Baghdad government and Iraqi army "through a joint operations room" to defeat the jihadists, with neither side crossing borders, he added.
"We have rearranged our ranks," Lilwa al-Abdallah, spokeswoman for the offensive, told Reuters.
US Defense Secretary Jim Mattis said last week that he expected a "re-energised" effort soon against the ultra-hardline militants in eastern Syria.
Syrian fighters, backed by US air strikes and troops, have dealt heavy blows to IS but the jihadists still hold a swathe of land along the desert frontier with Iraq. As they lose more territory of their self-proclaimed "caliphate", militants are expected to revert to guerrilla tactics.
US support for Kurdish forces in Syria has infuriated Turkey, which sees the YPG militia - part of the SDF - as an extension of an outlawed Kurdish insurgency at home.
Ankara's offensive to expel the YPG from Afrin - where the United States has no presence - led to a pause in the campaign against IS. Turkish forces captured Afrin in March.
Abu Khawla said the 1,700 SDF fighters which had been deployed there have now returned to the east. The assault on Afrin "distracted from eliminating Daesh", he said, using the Arabic acronym for IS.
"It had a very big and wide impact on the liberation, which was stalled for months."