So, Russian arms going to Syria. Russian fleet in the Eastern Med with a base in Syria. Iran offering military support to Syria. Turkey and others threatening a "no fly zone" over Syria.
What happens when Iran ups its offer and sends troops into Syria (through Iraq) as "peacekeepers" and extends its air patrols over Syria?
No-one in Iraq to stop them, and the northern Iraqi population is Shia and sympathetic to Iran anyway - so no problems for Iran in making the transit.
Longer term, if Iran can't export oil via the Gulf / Red Sea / Suez due to European sanctions, a new Russian built pipeline across Iraq and Syria to the Med can't be too difficult given their experience with the pipelines around the Caspian