There is a point at which a conflict shifts from a proxy war and into an actual war. That would be the point at which both sides are no longer just supplying weapons and intelligence, but are actually on the ground fighting each other.
Iran is all in on the Shiite side of the table.
Western intelligence officials say that Iran’s president, Mahmoud Ahmadinejad, has personally sanctioned the dispatch of the experienced officers to ensure that the Assad regime, Iran’s most important regional ally, survives the threat to its survival.
In addition, Iran has shipped hundreds of tons of military equipment, including guns, rockets, and shells, to Syria through the regular air corridor that has been established between Damascus and Tehran.
On the Sunni side, Turkey may be all in as well, matching Iranian officers with Turkish officers.
Turkish army officers have assumed direct command of the first two Syrian rebel brigades fighting Bashar Assad’s government forces,
That report comes from Debka, which can occasionally be erratic, but it’s plausible. And if it hasn’t actually happened yet, it will happen.
Iran and Turkey are both being drawn into an escalating civil war in Syria. And if the civil war keeps going, then eventually both sides will be fighting each other. The wild card is Western intervention ,which the Sunni side is desperately counting on. Without NATO though, the locals will have to settle this themselves and it will be long and bloody.
Aside from the Sunni-Shiite element, there is the nationalistic issue. The Persian and Ottoman empires have deep regional significance and both are squabbling over a region in conflict. Syria is not a people’s revolution, it’s a fight over whose puppet Syria will become.
This war became inevitable when Syria allowed itself to become Iran’s puppet and shifted into the Shiite side in a developing regional conflict between Sunni and Shiite Islamists. But even without the Islamist ascendance, Syria began acting like Lebanon and it was only a matter of time until regional powers began treating it the way that it had treated Lebanon.