The killing of the enigmatic military chief of Lebanon's Hezbollah remained shrouded in mystery Friday, with his powerful Shiite militant movement giving out no information.

- What we know so far -

Mustafa Badreddine was in a warehouse near Damascus airport when it was rocked by a blast on Thursday night, a Syrian security source said. 

No aircraft was heard before the explosion and no one knew he was there, the source said.

The airport and its surroundings adjoin an area of fighting around the Sayyeda Zeinab shrine, which is revered by Shiites around the world.

The Syrian army controls the area, and Iranian and Hezbollah fighters are also present in force. 

The closest rebel positions are seven kilometres (four miles) away in the Eastern Ghouta area.  

- Who is Mustafa Badreddine? -

The military commander was aged around 50 and hailed from the south of Lebanon, bordering Israel.

His military career started in the ranks of the PLO's Fatah movement. Following Israel's invasion in 1982, he joined the Hezbollah movement newly created by Iran's elite Revolutionary Guards. 
He was jailed in Kuwait for attacks on the French and US embassies in 1983.

Shiite activists highjacked a plane in Kuwait in 1984 and a TWA aircraft to Beirut the following year to demand his release, before he finally escaped from jail during Iraq's 1990 invasion of Kuwait. 

He has been on trial in absentia before a special tribunal in The Hague accused of masterminding the 2005 bombing that killed Lebanon's former prime minister Rafiq Hariri.

Badreddine replaced his mentor and brother-in-law Imad Mughniyeh as Hezbollah's security chief after the latter was killed in a February 2008 attack in Damascus.

And when the Shiite movement intervened in support of its ally President Bashar al-Assad in Syria's civil war, he became head of military operations.

- Will Hezbollah be affected? -

Most experts agree that his death will have only a limited impact on Hezbollah. 

"Despite the importance of Badreddine, Hezbollah's highest ranking secret operative and the man considered responsible for battlefield strategy, I doubt this will impact their operations in Syria," said Maha Yahya, acting director of the Carnegie Center for the Middle East.

"Hezbollah is not a one-man operation, and it is part of a larger entity that is also connected to the Iranian command," she said.

Nicolas Pouillard, a researcher at the French Near East Institute, said the impact of his death would have "symbolic and psychological" consequences.

"He was a Hezbollah veteran -- one of its main military leaders," he said.

- Who did it? -
Hezbollah has not immediately accused its sworn enemy Israel of carrying out the attack, unlike in previous instances.

Pouillard said: "For the moment, Hezbollah is not accusing any party."

But "Israel and factions of the (Syrian) opposition could ... be involved in this assassination," he said.

It "occurred on the outskirts of Damascus, near the airport area, which is held by the regime", he said.

"There was therefore some intelligence gathering beforehand, which could implicate several Syrian and regional parties."

Lebanese academic Waddah Charara, who has written a book on Hezbollah, said the Shiite group finds itself in a difficult position.

"To accuse Israel of having carried out an aerial campaign is throwing into doubt Russia's efficiency in protecting Syria's air space," he said.

Assad's longterm ally Russia has since September carried out air strikes in Syria in support of regime troops.

"One should not rule out that this assassination could be the result of tensions between the regime, Russia and Iran -- or even rebel shelling," he said.

Hezbollah's number two Naim Qassem has said the results of an investigation into the killing would be announced at the latest on Saturday morning.

- Syria conflict -

Badreddine's death is unlikely to affect Hezbollah's involvement on the side of the regime in Syria's brutal five-year conflict.

Hezbollah has sent thousands of combattants -- between 5,000 and 6,000, according to Charara -- since 2013 to help fight both rebels and jihadists.

They send 2,000 fighters at a time in rotation, he said.

Experts say Hezbollah has lost 1,000 to 2,000 fighters.

"It remains to be seen if and when Hezbollah will reach a tipping point where the losses in Syria begin to outweigh the benefits of direct military involvement," said the Carnegie Center's Yahya.

Source :AFP