A ruthless attack that proves Assad is not invincible

After 16 months of brutality, Syria's President yesterday experienced it at his own door

Crowds in Damascus celebrate the news of yesterday’s bomb strikes (AP)

The sounds of gunfire and explosions have moved ever nearer to the presidential palace in recent days, piercing the bubble in which the ruling Assad dynasty lives. But even as the fight drew closer, it is unlikely that President Bashar al-Assad could have imagined yesterday would bring such a devastating strike on his inner circle.

During the siege of Homs earlier this year the presidential couple continued to shop for luxuries, cracking jokes about the revolution as the Syrian army attempted to crush its enemy. But the Free Syrian Army (FSA) brought the fight to their door step, leaving the seat of power in turmoil.

Although hugely outgunned and outnumbered, the opposition managed its most daring strike yet as a powerful explosion ripped through the meeting room at the national security building. While initial reports said the attack was a suicide bombing, an FSA source said a bag of C4 explosives had been smuggled in to the meeting room by a bodyguard to Assef Shawkat, the President's brother-in-law and lynchpin of the regime, and detonated remotely. Regardless, the fact remains that this must have been the work of an insider with high-level security clearance.

The deaths of at least three of the regime's most senior figures hurts on multiple levels. The killing of Assef Shawkat, the Deputy Defence Minister and husband of Assad's sister, Bushra, will be a personal blow for the Syrian leader. Killed alongside the Defence Minister, Dawoud Rajha, and the Assistant Vice-President,Hassan Turkmani, the men were members of a national security committee which meets at least once a week to plan how to crush the uprising. Their experience and knowledge of the situation on the ground is irreplaceable.

There were conflicting reports about the fate of a fourth senior figure, the country's Interior Minister, Mohammad Ibrahim al-Shaar, who was also caught in the blast, for which both the Free Syrian Army and an Islamist group called Liwa al-Islam claimed responsibility. Syrian state television reported last night that he had been killed, but another pro-regime channel contradicted the claims, saying only that he had been wounded. Hisham Ikhtiyar, the head of national security, was also wounded in the blast while rumours swirled late last that the President himself may have been injured.

Blaming the attack on "terrorists hired by foreigners", the army flooded into the neighbourhoods from which the FSA has launched a four-day assault on the regime's stronghold, which it has dubbed Operation Damascus Volcano. Helicopters used machine guns to fire on opposition neighbourhoods including Kafr Souseh, according to activists, while pro-government militias were also said to have attempted to storm the southern suburb of Assali and central Midan neighbourhood.

While activists streamed footage from behind FSA lines, for the first time Syrian state television also screened footage of the battles in the capital, showing young men in army fatigues firing from behind stacks of sandbags. In a tactic used by Bosnian Serb forces during the siege of Sarajevo, government troops used anti-aircraft guns with their barrels pointed along the ground to wreak devastation. Compounding the pressure on the regime large numbers of defections were reported, with the Local Co-ordination Committees claiming that 60 soldiers had rebelled in Homs and 30 in Aleppo. Protected by rebel guns and emboldened by the day's developments, thousands of protesters took to the streets of the capital chanting for the overthrow of the government.

"God willing, this is the beginning of the end of the regime," said Riad al-Asaad, a rebel commander in Turkey. "Hopefully Bashar will be next."

While events moved rapidly on the ground there was little sign yesterday of progress in the diplomatic impasse. A crucial vote on Syria at the UN Security Council was postponed at the urging of the UN-Arab League envoy, Kofi Annan, as it became clear that Russia would veto a Chapter 7 resolution drafted by the UK and backed by the West. The draft would level sanctions at the regime if the army is not pulled back from population centres within 10 days and could pave the way for military intervention.

The Russian government remains adamant that sanctions would cross a "red line" on Syria. The Kremlin instead wants to introduce its own resolution asking for backing for a peace plan put forward by Mr Annan, which the US, Western Europe and the Arab League says is effectively "dead in the water" after failing to halt violence from regime forces. The Security Council has until tomorrow to decide whether to extend the mandate of the 300-strong observer force in the country.

As the White House added 29 senior officials, including most of Assad's cabinet, to an official blacklist, US Defence Secretary, Leon Panetta, and the British Foreign Secretary, William Hague, said that the Damascus bombing illustrated the need for a UN-enforced ceasefire. Mr Panetta said last night: "This is a situation that is rapidly spinning out of control."