Relations between Saudi Arabia and Iran are at their worst for nearly 30 years.
Tensions have spiralled following the execution of Saudi cleric Nimr al-Nimr, the subsequent setting ablaze of the Saudi embassy in Tehran, and Riyadh's expulsion of Iranian diplomats.The struggle between Riyadh and Tehran for political and religious influence has geopolitical implications that extend far beyond the placid waters of the Gulf and encompass nearly every major conflict zone in the Middle East.
Most notably, perhaps, the crisis means prospects for a diplomatic breakthrough in Syria and Yemen now look much more remote, just as international momentum for negotiations seemed to be on the verge of delivering results.