Having long denied its engagement in Syria behind president Bashar Al Assad, Hizbollah has committed itself this week to the fight for the strategic small town of Qusayr.
Hizbollah sends hundreds of fighters to Qusayr as Syria's violence spreads
HERMEL // On a country road in Lebanon's north-east, traffic is heavy. Ambulances screech by, sirens blaring, and cars packed with mourners follow coffins as Hizbollah brings wounded fighters home from Syria, and its dead.
With the bodies from the battle over the border at Qusayr, comes the violence, as civil conflict between Syria's Iranian-backed ruler and Sunni rebels spreads across the Middle East. The Shiite militia's drive to save Syria's president is testing Lebanon's own fragile, sectarian peace and raises the stakes in a broader struggle for power in the region and the wider world.
Having long denied its engagement in Syria behind president Bashar Al Assad, Hizbollah has committed itself this week to the fight for the strategic small town of Qusayr, sending hundreds of men and losing dozens wounded and between 20 and 50 killed.
Their coffins, escorted by stern-faced Hizbollah gunmen and corteges flying the movement's yellow banner, stream back to Shiite villages in the north-eastern Bekaa Valley, ending any discretion about its backing for Al Assad's regime and his Alawite minority.
For all that staff at hospitals taking in the wounded around the town of Hermel keep doors closed to journalists and insist that there is nothing to see, the war has widened its scope.
With Sunnis and Alawites in the nearby Lebanese port of Tripoli also engaged in the fiercest communal fighting yet, the spread of violence beyond Syria is accelerating.
Already sectarian killing has surged in Iraq, bombs have hit Turkey and Israeli air strikes in Syria targeted Iranian arms for Hizbollah while world powers remain divided among themselves as they try to push Syria's rivals into holding peace talks.
For Rami Khouri at the American University of Beirut, Hizbollah's Syrian venture risks rebounding into Lebanon and could even - in a very worst case - fuel a regional war.
"It would vastly increase the likelihood of massive internal Lebanese strife between pro- and anti-Hizbollah groups, broadly pitting Sunnis and Shiites against each other while also inviting another major war with Israel, or possibly participation in an American-Israeli/Iranian-Syrian war."
Rafik Nasrallah, a political analyst in Beirut, who is close to Hizbollah, said the movement had been obliged to intervene in Syria to protect Lebanese interests.
"There is no Lebanese state, there are groups in the security apparatus here that serve different regional powers or countries," Mr Nasrallah said. "Hizbollah's job is to protect Lebanon and its borders, it is doing what it has to do."
On the frontlines, the intervention appears to have hardened sectarian attitudes among rebels fearful of losing a key position.
"The fall of Qusayr will completely change the struggle in Homs province from a revolution into a major assault on Alawites and Shiites wherever they are," said a fighter who used the name Abu Bilal and spoke from Homs.
Hizbollah's forces are tiny beside the tens of thousands of troops that Mr Al Assad can call on even after Sunni desertions from his army. But it does have thousands of guerrillas, many of whom saw action against Israel in 2006.
Hizbollah's alliance with Mr Al Assad has been criticised by Arabs who once supported it for its stand against Israel. But its leaders remain unapologetic, arguing it is crucial to their "axis of resistance" - the term it uses for its anti-Israel alliance with Tehran and Damascus.
The former Lebanese prime minister, Saad Hariri, a Sunni with powerful allies in Saudi Arabia, said this week: "Hizbollah has chosen to copy Israeli crimes against Lebanon and its people and apply them to the inhabitants of the Syrian city of Qusayr."
Hizbollah, in turn, has sought to shore up its pan-Arab credentials by accusing its rebel enemies at Qusayr of being sponsored by Israel and western powers - thus justifying its intervention as part of its "resistance" to Israel.
"Israel is in Qusayr. The attack on Syria is all part of an Israeli, foreign-led attack on Syria," said Amin Hateit, a Lebanese commentator close to Hizbollah. "This is a party of ideology, not nationalities. So wherever there are enemies to those beliefs, its fighters will go. They go voluntarily."
It is unclear how willingly Lebanese Shiites will go on fighting and dying in Syria like Radwan and Ali Qassem Al Attar, brothers who fell at Qusayr a few days ago and in whose memory yellow Hizbollah banners now fly at a spot near their home, off a dusty side road in the Bekaa Valley.
A security source close to Hizbollah believes it cannot count on unlimited backing from its local supporters. Leaders had calculated, he said, that the movement could afford to lose several dozen men at Qusayr, due to its strategic importance.
But if the battle drags on, recruitment might suffer, he said.
"Soon they could start asking 'Why should we fight and die for Syrians?' "