BEIRUT (REUTERS) - A mounting death toll in President Bashar al-Assad's armed forces is causing alarm among some government loyalists who are worried about Islamic State's territorial gains and are turning their anger on the authorities in Damascus.
The execution of scores of Syrian soldiers taken captive by Islamic State at an air base in Raqqa province has triggered unusually harsh social media criticism of the Damascus government by people who have taken its side in the civil war.
Some, including one of Assad's cousins, have called for the resignation of the defence minister, blaming him for the loss of the Tabqa air base that represented the government's last foothold in a province otherwise controlled by Islamic State.
With the flow of information from Syria greatly restricted, it is not possible to gauge how widely such sentiment is felt. And it is not the first time the Syrian government has faced criticism from its supporters during the three-year conflict.
But it points to a potential pressure point for Assad, who draws support from minority groups including his own Alawite community for whom Islamic State is an existential threat.
"I demand the resignation of the minister of defence, the chief of staff, the air force commander, the minister of information, and whoever is responsible for the fall of the Tabqa military airport," Duraid al-Assad, the cousin of Bashar al-Assad, wrote on his Facebook page.
Duraid is a son of Rifat al-Assad, who left Syria after being accused of attempting a coup in the 1980s against the late president Hafez al-Assad.
Contacted by Reuters via his Facebook page, Duraid said he currently lives in Syria.
His status was endorsed more than a thousand times.
Dozens of people wrote comments expressing their agreement.
From Damascus, Islamic State may have seemed a distant threat until recently. Raqqa city, Islamic State's stronghold, is 350km north-east of the capital.
The government has been focused on shoring up control over a corridor of territory in western Syria stretching north from Damascus up to the coast.
Islamic State has meanwhile been expanding its control in the east. Besides Raqqa province, it has taken most of Deir al-Zor, securing control over oil fields and the Euphrates river.
But now, strengthened by military hardware seized from the Iraqi army in June, Islamic State is advancing westwards.
Since June, engagements between Islamic State and government forces have cost the lives of hundreds of loyalist fighters, according to the Syrian Observatory for Human Rights, which monitors violence in the civil war.
Syrian state media rarely mention government casualties.
Families of missing soldiers have turned to social media in an effort to locate them.
In the days before Islamic State fighters seized the Tabqa air base on Sunday, state media had reported on the efforts to defend it.
On Sunday, the day the airport fell, it reported that government forces had staged a successful evacuation.
But footage subsequently released on YouTube and broadcast by Arab news channels showed Islamic State fighters executing scores of Syrian soldiers after forcing them to march in the desert in nothing but their underwear.
Islamic State said it had killed 250 soldiers taken captive at the air base.
"They captured 250 soldiers in Tabqa and are saying they have executed them. Oh, you officials, and you leaders, how could you sacrifice 250 soldiers like that?" said one comment posted on a pro-Assad Facebook page by someone whose user name - "Cub of Assad" - indicated strong pro-government sympathies.
Western officials and anti-Assad activists have accused the Damascus government of leaving Islamic State to its own devices, allowing it to expand in a ploy aimed at crushing less radical opposition forces.
The West has rebuffed a Syrian government offer to act as a partner in a war on Islamic State.
The group has meanwhile been advancing in the countryside north of Aleppo, edging closer to Syria's second city where government forces and allied fighters are battling to crush other insurgent groups.
Alawites living near the coast are worried by both Islamic State and recent attempts by Al-Qaeda's Syrian arm, the Nusra Front, to advance closer to their areas, said an anti-Assad Alawite who lives near the coast, speaking via Skype.
"The Alawite community is afraid. People here are angry. They're upset that the government abandoned those soldiers. They are also worried now that the battles are coming so close," said the activist contacted via the internet who spoke on condition of anonymity because of fears for his safety.
Some analysts argue that even if there is dissent in the Alawite community, the threat posed by Islamic State will bind it more tightly together rather than cause divisions.
But a Western official said there appeared to be growing doubts among Assad supporters about whether his military could confront the threat posed by the radical Islamists if they continue to expand in the way they have been.
"I think a lot of Christians and Alawites are saying 'wait a minute, what about a plan B?'" said the official.
Salem Zahran, a Lebanese journalist with close ties to the Syrian government, said the executions at Tabqa would only strengthen the government's narrative.
"There is the angle that you lost a position, true, but there is another angle that you are proving once again that the opposition, at the forefront of which is Islamic State, is a bloody opposition that is murdering people," he said.
Criticisms of the government had been made before, he said. "But they don't last, and then die away."