The blast was the second blow to Syrian control in West Beirut within four days.
Baalbek is the main town in the Bekaa, which is under Syrian military control.
Israel claimed that the treaty placed Lebanon under total Syrian control and as such posed a major security threat.
In 1975, following the 1974 ceasefire agreement, Israel returned a narrow demilitarised zone to Syrian control.
The alternative, which came to pass when the American troops left, was Syrian control, for which everyone in the region is still paying the price.
The task was to "retake the Golan" after three days of Syrian control.
However, on 16 May the villages came under Syrian control, and many inhabitants returned.
So they welcomed the calm that Syrian control brought them.
Two Israeli sappers were sent to mine the area of the quarantine station, but did not know that it was already under Syrian control.
Many say it is better to stay alive under Syrian control than to die under Christian bombardment.