IS counter-attacks to defend north Syria stronghold

- Clashes raged around a key northern Syrian town today after the Islamic State group launched a counter-attack to fend off a US-backed advance near the jihadists' stronghold Raqa.
Backed by air power from the international coalition bombing IS, the Syrian Democratic Forces are laying the groundwork for an assault on the heart of the jihadists' so-called "caliphate".
A key part of the campaign is the battle for the IS-held town of Tabqa on the Euphrates River, as well as the adjacent dam and military airport.
The SDF seized the Tabqa airbase late Sunday and began moving north towards the town itself, but IS fighters began pushing back today, said the Syrian Observatory for Human Rights.

"The fighting is a result of IS launching a counter-offensive to exhaust the Syrian Democratic Forces around the Tabqa military airport," said Rami Abdel Rahman, who heads the Observatory.
The SDF was working to "consolidate its positions" near the airport ahead of a final push for the town, he said.

IS launched the attack with a car bomb targeting SDF forces stationed near the airport, the alliance's media arm said.
Fierce clashes broke out but the SDF held back the attack and managed to seize some ammunition and rocket stores from IS, according to pictures published by the SDF.
SDF fighters are also bearing down on the Tabqa dam after capturing its northern entrance on Friday from IS fighters.

The fight around the structure has been backed by forces from the US-led coalition, with American-made armoured vehicles bearing the markings of the US Marine Corps seen moving along a nearby road.
An AFP correspondent at the dam today said it was generally quiet around the dam itself, despite the occasional IS-fired mortar that landed in SDF-controlled parts of the riverbank.
Planes could be heard above as SDF forces patrolled the northern entrance of the structure.
Today, coalition forces could be seen standing near military vehicles less than two kilometres from the dam, their mortar rounds casually stacked nearby.
After a brief pause in fighting yesterday to allow technicians to enter the dam complex, SDF fighters resumed their operations around the structure, said spokeswoman Jihan Sheikh Ahmed.

"IS amassed its fighters and attacked our forces in the area, which forced us to respond and resume the operations to liberate the dam," she said.
Earlier this year, the United Nations raised concern about the prospect of damage to the dam in fighting, warning that water levels -- which put pressure on the structure -- were already high.