Russian arms 'to deter foreign intervention in Syria'

In a article written by BBC it says that Russia says it will go ahead with deliveries of a russian anti-missle system called S-300 anti-aircraft system to Syria. The Deputy Foreign Minister Sergei Ryabkov said that "the missles were a "stabilising factor" that could dissuade "some hotheads" from entering the conflict. It says further in the article that "Russia also criticised an EU decision not to renew an arms embargo on Syria" I find this very confusing because an arms embargo means that arms cannot be sold to Syria yet the Russians are going to deliver weapon systems to Syria this seems very odd. Even more disturbing is that the Israeli Defense Minister Moshe Yaalon told BBC that "Russian missle systems had not yet left from Russia." he continues on to say that "I hope they will not leave, and if, God forbid, they reach Syria, we will know what to do," he said. This is a concern to me because Israel is saying in a way that they would take measures to make sure that these missiles will not be a threat to outside intervention like the United States and the EU. The question I have is that if the missiles are sent to Syria and Israel does act what will the repercussions.