Analysis - Attack on Damascus "fortress" rocks Assad

The damage is compounded by Assad's failure to in speak in public to rally his forces. State television only showed footage of him swearing in his new defence minister, the first images of the president since the bomb attack. Assad's younger brother Maher al-Assad, commander of the army's elite units, has however remained out of sight.

Maher is the strongman of the Assad clan, but its strategic brain, the president's brother-in-law Assef Shawkat, was assassinated along with at least two other security chiefs in Wednesday's bomb attack that killed half of the government's six-member crisis council.

"The fortress of Damascus is no longer a fortress", said Fawaz Gerges, Professor of Middle Eastern Politics at the London School of Economics. "Psychologically this is a shattering blow to both Assad and his supporters".

"It must make Assad and everyone at the top unsure how safe they are from their own people", said Middle East columnist Rami Khouri. "This is a regime on its last legs".

The strike at the centre of power will further embolden the opposition, which has already taken its fight to the streets of central Damascus, vowing to liberate the capital from four decades of autocratic Assad family rule.

Scenes of armed rebels from the Syrian Free Army pushing back regular army troops and torching police stations in the capital were unthinkable just a few days ago. They represent a point of no return for many in the armed forces, from which more soldiers have defected since the bomb attack.

The blast not only wiped out important elements of Assad's inner circle but sent an unmistakable message to the president and his loyalists: They are no longer immune or invincible and the tipping point is getting closer.

Analysts say the spectacular attack would probably also trigger more defections of senior Sunni army officers and loyalists who feel they can no longer trust a leadership unable to protect itself or its people.

For most, it is not just that the rebels managed to hit the top political and military leadership and members of Assad's family and clan, but that they were also able to infiltrate the fortress-like security apparatus in Assad's backyard.

"It is an enormous shock to the Assad system," said Khouri.

"This is the dynamic that brings down the regime when people lose confidence in the ability of the regime to protect itself. It looks a weak and frail regime that has lost the confidence of the people," he said.

"This will mark the beginning of the end of the regime. How quickly it will end, we don't know exactly."

The 46-year-old Assad is left with just a handful of loyal confidants he can trust, including his younger brother Maher, who commands the Republican Guard and the Fourth Division.

Maher's units are tasked with operations to crush the 16-month-old uprising, which followed revolutions in Tunisia, Egypt, Libya and Yemen.

The aftermath of Wednesday's attack suggests a government in disarray. The funeral arrangements of the leaders killed remain a mystery in a country where religious custom dictate a swift official burial. Assad's silence speaks volumes.

Most watchers of Damascus believe that countdown for Assad's demise has begun but they are unclear how he might go.

The question remains whether Assad, who took power after his father's death in 2000, would fight to the finish and risk being captured and killed like Muammar Gaddafi, or whether he would board a plane and go into exile, like Zine al-Abidine Ben-Ali of Tunisia.

Reacting to the explosion, U.S, Defense Secretary Leon Panetta said the situation in Syria was "spinning out of control". He also took the opportunity to warn Assad that he would be held responsible if the government failed to safeguard its chemical weapons sites.

The stakes are high for Syria, entangled in a civil war and whose population comprises a combustible sectarian and ethnic mix of Sunnis, Alawites, Kurds and Christians.

It is not even clear who would seize power if Assad's rule collapsed in the absence of a credible political opposition or a Libya-style transitional government. Armed rebels, many of them led by Islamist Jihadists, are likely to have the upper hand.

Syria could end being torn apart into sectarian cantons with Kurds in the north, Alawites along the coast, Druze in the southern hills and Sunnis elsewhere. Or it could plunge into sectarian warfare like Iraq after Saddam Hussein.

Western leaders fear that the current conflict, which has been joined by al Qaeda-style jihadists, could destabilise Syria's neighbours: Israel, Lebanon, Turkey, Iraq and Jordan.

The ideal solution, analysts say, would be an international-sponsored transitional government that would represent all sides.

In the meantime, Assad's strategy in response to the growing rebellion is predictable, close allies and enemies say.

He would act ruthlessly to save his skin and his Alawite clan, a minority in a country of 21 million with a Sunni Muslim majority and which has ruled Syria since 1970.

"Assad must be a worried man. He will become more brutal but the more he uses force the more revolt against him. It will bring him down more quickly," Khouri said.

"He dug his own political grave. He will eventually go but he doesn't have the Yemen option" of a peaceful power transition, Khouri said, adding that he has not been indicted by an international tribunal so he could flee the country, possibly to Russia.

"Otherwise, he could be captured, killed or put on trial."

Wednesday's explosion appeared to be part of a coordinated assault on the capital that has escalated since the start of the week. Rebel fighters call it the "liberation of Damascus" after months of fierce clashes which activists say have killed 17,000 people.

Ahmad Zaidan, spokesman for the Higher Council of the Revolution's Leadership, an opposition group, said the blast was a major blow to the morale of Assad's 500,000-strong army.

"It's the beginning of the breaking of the chain, the regime has lost control now and those around Bashar al-Assad, whom he relied on, are gone. The regime's foundations have been shaken."

Rebels were dancing in the streets at their success in penetrating the capital and at the deaths of the security chiefs. Abdullah al-Shami, a rebel commander, said: "I expect a speedy collapse of the regime ... and it means we will not be in need of outside intervention, with the regime beginning to crumble much faster than we envisaged."

Yet some opposition figures said victory would not be easy.

"It is going to be difficult to sustain supply lines and the rebels may have to make a tactical withdrawal at one point, like they did in other cities," veteran opposition activist Fawaz Tello said from Istanbul.

"But what is clear is that Damascus has joined the revolt."

(Created by Samia Nakhoul; Editing by Giles Elgood)