Why has Syria had an uninterrupted record of attaching itself to radical causes and countries like Iran?
Syria is ruled by a besieged and insecure minority, the Alawites. About 12% of Syria's population, the Alawites are looked at by extremist Sunni Muslims as heretics. In the late '70s and early '80s, Sunni extremists came close to getting their way. During a 1982 Muslim Brotherhood insurrection in Hama, Hafez al-Assad felt compelled to flatten it in order to stay in power.
By joining Iran in the so-called "Islamic resistance" against Israel, Assad associated the Alawites with a cause larger than themselves. Since the Alawites cannot settle with Tel Aviv and survive the wrath of the Muslim Brotherhood, it remains reliant on its alliance with Tehran. The Alawites will risk war with Israel if they believe their survival requires it.