As the world's two biggest oil producers, Russia and Saudi Arabia working together have the potential to dominate the globe's petroleum markets. So far, that hasn't happened, as seemingly irreconcilable differences – and particularly US-Saudi relations – have kept them apart.

But all the smiles and deal-making last month between Vladimir Putin and Mohammed bin Salman, the youthful and ambitious Saudi deputy crown prince and defense minister, has some claiming that the two energy giants, driven together by geopolitical crisis, may bet set for a much closer relationship.

Some experts perceive signs of an "emerging partnership" driven by shifting global winds, in which Saudi cash helps Moscow dodge Western sanctions, while Russian arms, engineering expertise, and diplomatic support assist the energetic new Saudi king to wean his country from dependency on an increasingly uncooperative US.

But others argue that, while change is definitely in the air, the outreach is purely tactical and of limited intent on both sides. Vast differences remain, particularly over critical issues such as regime change in Syria and a big power-sponsored nuclear deal with Saudi Arabia's archenemy, Iran.