It was the first declared operation by the Democratic Forces of Syria which joins together a US-backed Kurdish militia and several Syrian Arab rebel groups, since it announced its formation earlier this month.
"We announce today the start of the first step in our military operations," a spokesman for the alliance's general command said in Arabic in a video statement posted on YouTube.
World powers and regional rivals are convening in Vienna to seek a solution to the four-year conflict in Syria that has escalated since Russia intervened a month ago with an intense air campaign.The Kurdish YPG has been working closely with the US-led anti-Islamic State coalition since early this year, and has to date proved Washington's most effective partner on the ground against IS in Syria.
The United States, which announced on Friday it was to station its first ground troops in Syria for the war on Islamic State, has dropped ammunition to rebels in the north of Syria but without specifying which group the aid was intended for.Hasaka province borders Iraq and Islamic State territory there, a crucial stronghold for the group. The YPG had pushed toward the border in previous fighting this year.