Qantar has been considered as a high-ranking member of the Lebanese resistance movement, Hezbollah.
He was killed during an Israeli raid near the Syrian capital Damascus early on Sunday.
Qantar spent 29 years in Israeli detention and was released from an Israeli jail during a prisoner swap between Hezbollah and Israel in 2008.
The Lebanese resistance movement has vowed that it would not leave Israel’s assassination of Qantar unanswered.
Hezbollah Secretary General Sayyed Hassan Nasrallah has said during a recent televised broadcast on Monday that the movement reserves the right to respond to this assassination.
Qantar has been organizing battles against extremist and militant groups such as Daesh and al-Qaeda linked al-Nusra Front across the region.