Intense fighting in Damascus raged for a fifth straight day, with Syrian troops desperate to dislodge rebel forces. Thousands of Syrians fled to Lebanon Thursday to escape the violence as helicopter gunships attacked rebel strongholds in city suburbs.

Despite this show of force, CTV’s Middle East Bureau Chief Martin Seemungal told 鶹ý Channel that a deadly rebel attack on Syrian President Bashar Assad's inner circle on Wednesday has shaken “their loyalty, the cohesiveness of the military – all those things that keep him in power.

“Things could unravel very quickly for him,” Seemungal reported from Jerusalem.

However, Seemungal noted, Assad still has enormous firepower and he is using it to fight for his life.

One expert fears Assad will start to use unprecedented violence to maintain his grip on power in the wake of the deadly rebel attack.

“The concern,” said Christian Leuprecht, associate professor of the department of political science at Royal Military College, “is that the Syrian regime will begin to see traitors in its own ranks, start purging people from within its own ranks and start to use unprecedented violence against anybody and any element within the regime and population it sees as adversaries.”

He said that as the regime runs short on ammunition, as more officers and soldiers defect, as the regime proves increasingly inept at putting down the rebel revolt, “they will resort to whatever means they feel they need to, to calm the rebellion.”

In addition to the fighting in Damascus, a handful of rebels took control of a Syrian border post near the Iraqi town of Qaim after clashes killed 21 Syrian soldiers, Iraqi army Brig. General Qassim al-Dulaimitold The Associated Press.

A new defence minister was quickly sworn in Thursday, vowing to crush the rebellion.

Leuprecht said there are two major concerns in the wake of the rebel attack. One is that Assad could use Syria’s stockpile of chemical and biological weapons in his fight for power. The other is that the Syrian situation could get even more chaotic with factions beginning to fight each other while Assad is still in power.

Two competing groups, the Free Syrian Army and the Islamic Brigades, are both claiming responsibility for the bomb that was detonated in a crisis meeting attended by members of Assad’s inner circle.

“I think this is what people are fearing: Different groups fighting each other, possibly even before the Assad regime falls,” Leuprecht said.

Leuprecht added that Assad’s low profile since the attack could lead to a power vacuum. Footage of Assad was shown on Syrian state television in an apparent attempt to show that he was alive and well and attending the swearing in of the new defence minister.

The TV announcement did not say where the swearing-in took place, nor did it show any photos or video of the ceremony, as it usually would.

Leuprecht said that it is likely Assad has taken a step back to protect himself and his family and that it’s possible that others will begin issuing orders, leaving the west unclear on who to negotiate with.

“Nobody is watching with greater concern than Israel,” he added.

“The Syrians have withdrawn troops from the Golan Heights and that opens up the area for potential attacks on Israel by Islamists. There’s now talk of a potential first strike by Israel on some of the chemical and biological weapons in Syria.

“So I think these are deeply troubling developments that go far beyond Syria and affect us all in the international community.”

For its part, the UN is working to develop a new resolution to combat the violence in Syria before the mandate of its 300-person monitoring team expires Friday.

After the rebel bombing of Assad’s security meeting, China and Russia vetoed a new UN Security Council resolution on Syria's crisis. This once again reflected deep divisions between China and Russia and the West on who is responsible for Syria's crisis and how to stop it.

The resolution would have imposed non-military sanctions against Assad's government if it didn't withdraw troops from populated areas within 10 days. It was tied to Chapter 7 of the UN Charter, which could eventually allow the use of force to end the conflict.

Russia and China oppose any moves that put the blame exclusively on Damascus or could lead to foreign military intervention in Syria.