Lebanese families drawn into Syrian conflict
As the Syrian conflict fans the flames of Sunni-Shia tensions in the wider Middle East, BBC Newsnight's Tim Whewell meets families in Lebanon already drawn into both sides of their neighbour's war.
Sectarian tension in Lebanon has risen sharply since the fall of the strategic Syrian border town of Qusair to government forces on 5 June, a victory won with the help of Lebanese Shia militant group Hezbollah.
About 100 of the militia's fighters are believed to have died in the battle. Many were from the eastern Bekaa valley, which sits just over the mountains from Syria, including Muhammad al-Siblani, a 24-year-old fighter training to be a medical technician.
Speaking to the BBC about her son's death, Muhammad's mother Ghada al-Siblani said: "The confrontation was face-to-face. There were only five metres (16ft) between him and the Takfiris, of course with machine guns and everything, so that's how our son was hit with bullets and martyred."
Takfiris - a word for Muslims who accuse other Muslims of apostasy - is the term Shias often use to refer to the Syrian rebels, implying that they are Sunni extremists.
Fears of attack
Although Hezbollah is a long-term ally of Syrian President Bashar al-Assad, ordinary Hezbollah supporters say it is the threat from Sunni extremism that is the main reason the militia is fighting in Syria.
"It was not a sacrifice for Bashar al-Assad. We never sacrifice for people," Muhammad al-Siblani's sister Nur, a psychology student, said of his decision to fight. "He went because he knew these Takfiris would come one day to his house, his family and his friends, and slaughter them as they did in Qusair."
Their father Yassir al-Siblani voiced similar concerns about the threat of sectarian attacks on Shias:
"We've seen what they've done in Iraq, the daily bombings. The United States went to Iraq in 2003 to install a democratic system, but what we saw was regular al-Qaeda attacks," he said.
In Syria, radical Sunni Islamist groups, including Jabhat al-Nusra, part of which is linked to al-Qaeda, have recently been at the forefront of fighting against the regime.
Western powers now considering arming the rebels say they want to direct supplies to more moderate groups in the Free Syrian Army. But Hezbollah and its political allies in Lebanon claim the West has knowingly allowed Sunni extremism to develop.
"This is an American plan par excellence," Fayez Shukr, leader of the Lebanese Baath Party, whose nephew Hassan died fighting with Hezbollah in Qusair said. "It is working to achieve its own interests, so it uses these groups - Islamists, Salafists, extremists who have become Takfiris - to ensure its control over the world."
Spectre of civil war
On the other side of the sectarian divide, leaders of the strict Salafist movement in Lebanon are calling on Sunni Muslims to join the struggle against the Syrian regime.
Sheikh Dai al-Islam al-Shahhal, a prominent Salafi leader in Lebanon's second city Tripoli, told the BBC that people should "sacrifice money and life" to confront what he described as a Shia plan to take over the Middle East.
"They will move on to besiege Saudi Arabia and other countries in the Gulf, to control the sacred places and the riches of that region, to rule the Islamic world, if they can, and become a world superpower," he said.
Sheikh al-Shahhal's son Zayed, aged 20, has just returned from fighting with the Syrian rebels in Qusair - partly against Iranians and fellow Lebanese from Hezbollah.
"We caught many of them, and killed them after interrogating them. We killed them with their IDs on - carrying their key to heaven," he said.
Intervention by the Lebanese army has ended a recent outbreak of inter-communal fighting in Tripoli between Sunnis and local Alawites - members of the Shia sect which Bashar al-Assad belongs to. But Sheikh al-Shahhal said that if there was no action by the international community against the Syrian regime, one result would be civil war in Lebanon.
Former Lebanese defence minister Albert Mansour described the chances of civil war there as "50-50".
He said "Hezbollah, which is capable of beginning a civil war in Lebanon, doesn't want to do it, and those who do want to do it - some Sunni parties, little extreme Sunni parties - aren't capable of it."
But his prediction for the region was more pessimistic:
"We are in a new situation in the Middle East, and if it continues like this I think we are going to have a war of 100 years between Sunni and Shia."