Iran remains the biggest backer of President Assad’s fight against three years of rebellion, as efforts to reach a political settlement have failed.

Actually, I just want to ask a question about current affairs. Why do Iran have the biggest backer of President Assad who is the president of Syrie?
rpshWhy ...
In over-simplified terms, there's a religious war going on in the Middle East. You can follow who supports whom by asking what religion each has. Nobody supports anyone from a different religion.

Assad is a Shia muslim, as is the majority of Iran. The beligerents (IS) are Sunni muslims. Overall there are a lot more Sunni muslims than Shia's, so I think that is one of the reasons that Iran backs Assad.
Teachers: We supply a list of EFL job vacancies
Got it, thank you so much!
 CalifJim's reply was promoted to an answer.