An alliance of Syrian Kurdish and Arab fighters has announced it has taken a strategically important town from so-called Islamic State (IS).
The Syrian Democratic Forces (SDF) said they had "completely liberated" the town and its nearby dam, which are 40km west of IS-stronghold Raqqa.
It comes a day after the US said it was going to arm members of the Kurdish Popular Protection Units (YPG), which are fighting for the SDF.
That decision has angered Turkey.
It considers the YPG an extension of the banned Kurdistan Workers' Party (PKK), which has fought for Kurdish autonomy in Turkey for three decades.
President Recep Tayyip Erdogan said the fight against the jihadists should not involve "another terrorist group".
But Washington disagrees and insists the YPG - which leads the SDF's alliance of Kurdish and Arab militias that has driven the extremists from about 6000 sq of northern Syria over the past two years, with the help of US-led coalition air strikes - is needed to capture IS-held Raqqa.
The Pentagon has previously armed only Arab elements of the SDF.
YPG spokesman Redur Xelil said the US decision would "provide a strong impetus" to all forces fighting IS, but noted it came "somewhat late".
If the SDF has been victorious in Tabqa, it will open up a new route to Raqqa, the BBC World Service's Middle East editor Alan Johnston said.
The fighting has been raging in the town for weeks, with IS suicide bombers and snipers putting up fierce resistance.
They have been holding out in the northern neighbourhoods, and in the structure of the nearby dam, which the UN had previously warned was risked flooding the area if it was damaged.
However, SDF spokesman Talal Sello conceded "combing operations are ongoing to ensure that the city is clear".