Indeed, Syria is a vital issue for Iran. For Iranians, an attack on Syria is a direct attack on Iran. And the Iranians are not mistaken. There is a strong and growing inclination in the West that means to deliver Iran a more complex punch. The breakup of the Syrian regime will deprive Tehran of a historic and essential security footing for the survival of its regime. Iran believes that it is in a proxy war with its enemies in Syria. I should say that to a large extent, this is a correct interpretation by Iran. Some of the countries that are pushing for a regime change in Damascus may have other strategic objectives. There is persuasive evidence on display that Iran will be the new target after Syria. Put another way: toppling the Bashar al-Assad regime is a strategic, military and political prerequisite of an assault on Iran.
Turkey has elected itself to be a frontrunner in the campaign for a regime change in Syria. This is wrong in itself, even if the Assad regime does fall one day. Turkey should have devised a more fine-tuned tactic for balancing morality and reality. If you implement an erroneous strategy, you might end up helping your enemy. The rise of anti-Turkey Kurdish cities in northern Syria is perfect proof of this. Having weakened Assad, Turkey now realizes that, ironically, it has helped the PKK-linked groups to gain autonomy in Syria.
However, the critical factor for Iran is indeed not the Kurds. Turkey has become a frontrunner in a proxy war in Syria, and this is seen as a direct attack on Iran's survival. Tehran believes that Turkey is playing a key role in Syria. In fact, the Syrian case has almost become a Turkey-Iran proxy war. It is no secret that both sides are supporting their allies in Syria. Yet, what Turkey and Iran are doing in Syria is not the typical pattern of their historic bilateral relations since the 16th century. The Syrian case is unique and has the potential to change the historic Turkey-Iran configuration. The irony is that Turkey is doing this with a very pro-Iranian government. The lesson is very clear: If your material capacities are limited, you should keep a certain distance between yourself and the superpowers and their agendas. Otherwise, their backwash may easily splash on you in some directions that are quite different from the ones you intended.
The Turkey-Iran proxy war on Syria is contributing to the formation of a new Middle East. It is the Middle East of sects and ethnicities -- the Turks, the Kurds, the Jews, the Sunnis and the Shiites. In such a setting, there is no room for neutrality. Any such action is counterproductive. Sectarian and ethnic groups approach you either as an enemy or a friend. No one is interested in the neutral or meditating actor, Turkey's role of choice in the last decade. Worse, Turkey may face serious difficulties in reviving its former status of a mediator state among the regional actors.