Israel would be the usual suspect in a large bombing like the one that ripped through a crowded residential street on the outskirts of Damascus, as some commentators suggested. However, Syrian officials refrained from pointing a finger at Israel and Interior Minister Bassam Abdul-Majid called it a terror attack, not an enemy attack, implying that suspicion falls on Islamist extremists.

Syria has recently concentrated forces along the northern border with Lebanon, ostensibly to prevent weapons smuggling and activists from infiltrating the country. It is doubtful if that is indeed Syria's intention, because preventing such smuggling does not require the deployment of such large forces.

It is more likely that Syria is planning to invade northern Lebanon, with the excuse of calming down the skirmishes in Tripoli and its surroundings. But the Islamist organizations saw the threat and hastened to demonstrate their ability to strike inside Damascus.

Meanwhile, Syrian opposition sources in exile accused the Syrian government of setting off the blast, arguing that it gave the regime an excuse to systematically crush the Muslim Brotherhood and affiliated factions.

Syria's main problem is weak counterintelligence, shown by its failure to prevent a series of terrorist attacks, including the killing of Imad Mughniyeh. Yesterday's bomb looked like either a "work accident" or a targeting error, as the perpetrators may have intended to strike a larger target, but it still undermines Syria's contention that the country is immune to terrorist attacks.

"Such an attack, unless it's the work of one of Syria's intelligence branches, encourages other terrorists to try their hand, and that's the main danger," a Lebanese commentator told Haaretz yesterday.

"Syria is no longer the impervious state it used to be, there are Iraqi refugees, Al-Qaida activists who have found asylum, extremist groups of all sorts and criminal gangs who would do anything for money. Two years ago one of these gangs stole the car of the interior minister, who is also responsible for public security."

Whether gangs, extremist organizations or Israel, Syrian intelligence is likely to be facing a new shake-up similar to the one it underwent in 2002.