With all the post-Cold War geopolitical shifts in Eurasia, Russia, Turkey and Iran constitute a strategic triangle on the North-South axis. The three are interacting to get the largest share possible in the distributional conflict over the energy-rich Caspian region. The strategic importance of Iran remains untapped, and it aligns with Russia with respect to Turkey. If the EU continues to isolate Turkey and Russia and if US policy towards Russia becomes more predatory, the three countries, perhaps with support from China, might form a large Eurasian bloc, with adverse effects for global stability.
Criss, Nur Bilge & Serdar Güner (1999) Geopolitical Considerations: The Russia-Turkey-Iran Triangle, Security Dialogue 30 (3): 365–376.