Tabqa Dam (Syria) (AFP) - US-backed forces battled the Islamic State group around a key Syrian town Monday, after the capture of an airbase brought them closer to besieging the jihadists in their stronghold Raqa.
Backed by air power from the US-led coalition that has been bombing IS since 2014, the Syrian Democratic Forces are laying the groundwork for an assault on the heart of the jihadists' so-called "caliphate".
Operations are currently focused on the strategically important town of Tabqa on the Euphrates River, and the adjacent dam and military airport.
Late Sunday, Arab and Kurdish fighters from the SDF seized Tabqa airbase and pressed north towards the town itself.
Rami Abdel Rahman, head of the Syrian Observatory for Human Rights monitor, said the alliance was fighting north of the airport to reinforce its positions.
"The SDF could bring supplies to the airport in the coming days and use it as a launching point for additional military operations," he added, reporting "heavy strikes" in the area.
SDF spokesman Talal Sello said the alliance would "begin rehabilitating the airport after clearing out explosive devices" left behind by IS and said the base's main landing strip was seriously damaged.
- Fighting pause at dam -
Bolstered by air strikes and military advisers from the US-led coalition, SDF units are approaching Tabqa from the south via the airport and via the north near the IS-held dam.
The road to the dam was strewn with bits of burned vehicles and the casings of ammunition and the bodies of several alleged IS fighters lie in the shallow water of a canal, evidence of fierce fighting.
On Monday, the SDF observed a brief truce in fighting to allow a technical team to enter the dam after it was forced out of service the previous day.
An SDF spokesman later said inspections had been successful and the pause in fighting was now over.
"There is no damage to the dam or its function, the engineers have finished their work and confirmed that the dam has not been damaged, and on this basis the ceasefire ended," Jihan Sheikh Ahmed said in a statement.
A source at the dam had earlier said the work to assess and repair damage at the dam could last two or three days.
The UN has warned that damage to the dam "could lead to massive scale flooding across Raqa and as far away as Deir Ezzor" province downstream to the southeast.
IS issued warnings through its propaganda agency Amaq that the dam "is threatened with collapse at any moment because of American strikes and a large rise in water levels".
The US-led coalition denied the dam had been "structurally damaged" and said it was "taking every precaution" to ensure its integrity.
The SDF launched its offensive for Raqa city in November, seizing around two thirds of the surrounding province, according to the Britain-based Observatory.
At their closest point, they are just eight kilometres (five miles) from the city, to the northeast.
But they are mostly further away, between 18 and 29 kilometres from Raqa.
- Rebels quit Homs district -
Syria's conflict began with protests against President Bashar al-Assad in 2011 but has turned into a brutal war pitting government forces, jihadists, rebels, and Kurds against each other.
In addition to the US-led coalition's bombing campaign, Russian warplanes are carrying out air strikes in support of Assad's government.
On Monday, a spokesman for the Islamist rebel group Ahrar al-Sham told AFP it shot down a "Russian helicopter" over a government-held town in the northwestern province of Latakia.
But a spokesman for Moscow's forces in Syria, headquartered at the Hmeimim air base in Latakia, said Monday that all Russian aircraft inside Syria were safely at their bases or on missions.
Russia's air support has helped Syrian government forces regain the upper hand in swathes of territory across the country.
Assad's government has also relied on "reconciliation" deals, under which rebels agree to quit territory in exchange for an end to siege or bombardment, and safe passage.
On Monday, evacuations from the last opposition-held district of the central city of Homs resumed under a similar deal, SANA state news agency reported.
Homs governor Talal Barazi told AFP that around 1,900 people left Waer on Monday, 670 of them rebels.
UN-mediated talks between government and rebel representatives continued Monday in Geneva, aimed at bringing an end to the war that has killed 320,000 people.
Speaking in the Swiss city, High Negotiations Committee chief Nasr al-Hariri stuck by the opposition group's long-held demand that Assad cannot have any role in the transition and future of Syria.
The UN's envoy Staffan de Mistura was in Jordan on Monday to brief an Arab League meeting on the talks.