Lebanon`s Hezbollah announced Friday that its top military commander had been killed in an attack in Syria where the Shiite militant group has deployed thousands of fighters backing the Damascus regime.
Hezbollah said it was still investigating the cause of the blast near Damascus airport but it did not immediately point the finger at Israel as it did when the commander`s predecessor was assassinated in the Syrian capital in 2008.
The death of Mustafa Badreddine, who had led Hezbollah`s intervention in support of President Bashar al-Assad`s regime since the start of the five-year war, came as a fragile truce in Syria teetered on the brink of collapse.
A six-day-old ceasefire in battleground second city Aleppo expired early Thursday without being renewed and rebel sniper fire on the city`s government-held sector killed two civilians, one a woman, a monitoring group said.
Heavy air strikes pounded Al-Qaeda`s Syrian affiliate Al-Nusra Front in its Idlib province stronghold in the northwest, killing 16 fighters including a senior commander.
Badreddine, who was in his mid-50s, was a key player in Hezbollah`s military wing.
He was on a US terror sanctions blacklist, was a key suspect in the 2005 assassination in Beirut of Lebanese ex-premier Rafiq Hariri and was one of Israel`s most wanted men.
The Iran-backed Hezbollah did not say which of Badreddine`s many enemies it held responsible for his death.
"According to preliminary reports, a large explosion targeted one of our positions near Damascus international airport killing brother commander Mustafa Badreddine and wounding other people," it said in a statement."We are going to pursue an inquiry to determine the nature and causes of the explosion and ascertain whether it was the result of an air strike, a missile or artillery fire."
His funeral was to be held in Hezbollah`s stronghold in the southern suburbs of Beirut at 5:30 pm (1430 GMT), the movement announced.
Badreddine`s predecessor, Imad Mughniyeh, his cousin and brother-in-law, was killed in Damascus in 2008 in an attack that drew immediate threats by Hezbollah of heavy retaliation against Israel.
It made no such threats after Badreddine`s death.
Israel made no comment, as was also the case in 2008, but Israeli media underlined Hezbollah`s failure to apportion blame.
But Hezbollah`s Al-Manar TV listed Israel among the enemies of the group.
"The enemies of our great martyrs are known, the Zionists (Israel), the Americans or the takfiris (Sunni Muslim extremists who considers Shiites heretics)," it said.
Hezbollah lawmaker Nawwar al-Sahili told the network it was too soon to prejudge the results of the investigation into Badreddine`s death, but noted that the group faces "an open war" and "will retaliate at an opportune moment".
In its 2012 terror blacklisting of Badreddine, Washington charged that he was the key pointman for Hezbollah`s operations in Syria alongside major foreign backer Iran in support of Assad`s regime.
"Badreddine is assessed to be responsible for Hezbollah`s military operations in Syria since 2011," the US Treasury Department said, adding that he liaised personally with Assad.The pro-Hezbollah Al-Akhbar newspaper said Badreddine was killed on Thursday night.
Damascus airport is east of the capital in an area where various rebel groups have a strong presence, although pro-government forces have secured the highway to it for the past two years or more.
Hezbollah`s intervention was vital in shoring up Assad`s regime at its lowest point in the war against rebels backed by Gulf Arab and Western countries.
Its fighters secured most of the Lebanese border region, cutting vital rebel supply lines, and reasserted government control in most of the southern suburbs of Damascus, including the Sayyida Zeinab Shiite shrine district, revered by Hezbollah`s followers and by its Iranian backers.
In Beirut, Hezbollah expert Waddah Charara noted that Badreddine had been also responsible for training Shiite militiamen in Iraq and had a direct link with Iran.
His death comes months after another Hezbollah figure, Samir Kantar, was killed in an December 2015 air strike near Damascus which the group blamed on Israel.
Moscow`s intervention last September in support of its Damascus ally greatly expanded the military coalition backing it.
Russian officials have vowed to work closely with their US counterparts to salvage a February ceasefire between pro-government forces and non-jihadist rebels that was teetering on the brink on Friday after the Aleppo truce collapsed.
That deal had sharply reduced a surge in fighting in Syria`s pre-war commercial capital that had killed more than 300 civilians.