Syria’s Kurds on Thursday declared a de-facto federal region in Kurdish-controlled territories in northern Syria, triggering condemnation from both the Bashar Assad-led government and rebels, as well as the U.S., which warned against such “unilateral” declaration.

“We’re committed to the unity and territorial integrity of Syria,” U.S. State Department spokesman John Kirby said during a press briefing Thursday. “I don’t want to predict what the future’s going to look like, but right now, we do not support self-autonomous zones or self-rule in that regard.”

The Kurds already operate “autonomous administrations” in three enclaves bordering Turkey — Afrin and Kobane in the Aleppo province and Jazira in Hassakeh. The move to unite the three Kurdish-controlled provinces in a federal system, announced Thursday, is aimed at creating a self-run entity within Syria, similar to the one the Kurds have enjoyed in neighboring Iraq since 2003.

The new federal region, named Rojava after the Kurdish word for northern Syria, will also include many Arab and Turkmen areas captured from the Islamic State group.

However, the U.S.-backed rebel group, the National Coalition, warned against “any attempt to form entities, regions, or administrations that usurp the will of the people,” echoing the Syrian government’s opposition to the move.

“Any declaration to that effect would be without any legal value and void of any legal, political, social or economic effect as long as it does not reflect the will of the entire Syrian people with all their political leanings and social spectra, who are all committed to the national unity and territorial integrity of their country,” Syria’s state-run news agency SANA quoted a Foreign Ministry source as saying.

The declaration comes amid ongoing talks between the Syrian government and opposition representatives in Geneva. The talks, aimed at finding a political solution to end the protracted and bloody conflict, are not being attended by officials from the powerful Kurdish Democratic Party (PYD), reportedly at the request of Turkey, which considers the Kurdish PKK a terrorist group.

“Syria's national unity and territorial integrity is fundamental for us,” a Turkish foreign ministry official reportedly said, when asked about the Kurdish declaration. “Outside of this, unilateral decisions cannot have validity.”