BEIRUT: The Beirut car bomb that killed a top Lebanese security official will probably prove to be the most destabilising attack in Lebanon since the 2005 assassination of former prime minister Rafik al-Hariri.
What is less clear - and this is something that instils fear in a society still scarred by its 1975-90 civil war - is whether the attack was a reprisal or the start of a campaign of violence by Damascus and its allies, suspected by many Lebanese of trying to spread Syria's conflict across its borders.
Lebanon, which has yet to fully overcome its own wartime sectarian divisions, is too fragile to withstand being enveloped by a Syrian conflict that is beginning to mirror Lebanon's own slide into fratricidal bloodletting.
Wissam al-Hassan, the security official who died with seven others on Friday, was buried with full honours in an emotional state funeral on Sunday at the Rafik al-Hariri mosque, the heart of the former premier's reconstruction legacy in central Beirut.
The funeral turned into a political rally against Syria and its local allies in Lebanon.
Hassan is thought to have been targeted because in August, after a carefully planned sting operation, his Internal Security Forces intelligence unit arrested a former Lebanese cabinet minister close to Syrian President Bashar al-Assad.
The minister, Michel Samaha, is charged with transporting Syrian-assembled bombs to launch attacks on sectarian targets in Lebanon. Two Syrian officers, including General Ali Mamlouk, were indicted with Samaha in a humiliating blow to Assad and an unprecedented move against Lebanon's dominant neighbour.
Hassan also led the investigation into Hariri's murder and uncovered evidence that implicated Syria and Hezbollah, although both deny the charge. An international tribunal accused several Hezbollah members of involvement in the murder.
"There is a probability that this will be the start of a new period in which we will see more assassinations, bombings and other problems," said Sarkis Naoum, a columnist and Syria expert.
"Sectarian incitement is on the rise in the country and the killing of Wissam al-Hassan brought things to a head. We may be entering a very dangerous cycle. Anything might happen."
"It is not possible for the Syria conflict not to have implications on Lebanon. The Lebanese have entered the Syria war - one side is with the Assad regime and another is against it. They are fighting each other by proxy," Naoum said.
Tiny Lebanon, with its combustible sectarian mix, is being dragged into the Syria crisis with its rival Shi'ite and Sunni Muslims fighting on opposite sides.
Lebanon's Shi'ite Hezbollah group backs Assad, a member of the Shi'ite-based Alawite sect, in his fight against the Sunni-led insurgency. Lebanon's Sunnis and allied Sunni powers, notably Saudi Arabia and Turkey, support the Sunni rebels.
The killing of thousands of Sunnis in Syria has angered Sunnis in Lebanon and across the region.
Hassan's attacker did more than just kill Lebanon's most powerful intelligence brain, who collected data on all major players and uncovered several plots in recent years. The killer performed a public execution that sent a warning to all those who dared challenge Syria in Lebanon.
Some analysts said the devastating attack against Hassan's anti-Syria investigative establishment bore important similarities to the blast that targeted Assad's inner circle of security officials in Damascus in July.
"Whoever did this attack wanted to deliver a message that they can reach anybody, that they can hit the highest level of intelligence," said Beirut-based commentator Rami Khouri.
"Whoever did it wanted to say 'we can still strike'."
Opposition politicians and ordinary people at Martyrs' Square saw Syria's hand in the bombing.
"Wissam al-Hassan has one enemy - Bashar al-Assad," said Beirut MP Nouhad Mashnouq, a leading member of the March 14 opposition bloc led by Saad al-Hariri, son of the slain ex-premier.
Mashnouq said the cases Hassan had brought against Samaha and Mamlouk were actions against Syria unprecedented in the history of Lebanon.
Despite the accusations from Lebanese politicians, both the Assad government and Hezbollah condemned the bombing.
The immediate destabilising effect of Friday's blast can already be seen on the streets. Angry mourners tried to storm Prime Minister Najib Mikati's offices in central Beirut after the funeral, breaking through a security barrier and scuffling with police who fired in the air in response.
"Mikati leave, get out," chanted hundreds of protesters. They also chanted slogans against Assad, whom they accused of being behind the killing of Hassan.
The protesters blame Mikati's pro-Syrian and pro-Iranian-dominated coalition government for failing to provide security or respond effectively to the killing.