Just over a month ago, Ahmadinejad was a Guest/Observer at both the SCO conference in Bishkek and the military exercises in Russia.
Iran is a candidate member and an important potential cog in the wheel of ther SCO's drive for energy security around the Caspian region. The importance of Iran is different to different members, but factors as an Oil & Gas producer, vital East/West trade crossroads and permenant Warm water access for trade and military should not be underestimated.
In my view the SCO countries would do whatever they must to prevent the loss of Iran and its resources and a failure to recognise this would be a disasterous miscalculation.
I think we may have seen a demonstration of this commitment in Syria a few weeks ago: I have little doubt that the Israeli aircraft were looking for a passage throught to Iraq/Iran that did not compromise the Wests regional allies and that these planes had to abondon their mission in haste when challanged by unexpectedly sophisticated Air Defences. Whether these were simply equipment or "advisors" despatched by Russia to clog this gap, or (as I suspect) part of an initial deployment around the reopening Russian Naval base on the Northern Syrian Coast, is anyones guess.
If Air Defences have been moved into Syria, then for sure SCO AD Units will be in Iran too. Maybe other types of unit as well!