Tensions are mounting in the Middle East as the leaders of Saudi Arabia and Iran stoke a rivalry which has burned for hundreds of years.
Following the execution of Shia religious leader Sheikh Nimr al-Nimr by the Saudis, governments have sundered diplomatic links, accusations have been made and protests have filled streets.
The root of the problem is religion.
The Saudi royal family see themselves as protectors of the Sunni Muslim faith, while Iran’s clerics take the same view of themselves as leaders of the Shia Muslim faith.
The religious divide is not great, like sub-divisions of the Christian church, both sides share fundamental beliefs.
Religion hi-jacked for politics
The reality is religion has been hi-jacked by both sides as an excuse to push for more power in the region.
Sunni and Shia Muslims have lived together for hundreds of years, but now and then, sectarianism arises to mask the struggle beneath.
The sheikh was executed with more than 40 other Shia Muslims accused of terrorist activities in Saudi Arabia.
Iran also regularly executes Sunni Muslims for similar acts.
Both sides fund opposition groups within the other’s territory and sphere of influence.
Iran is thought to arm and fund Hezbollah fighters from Shia Lebanon in Sunni Syria, while Saudi Arabia and allies Jordan and United Arab Emirates take the opposite side.
Saudi Arabia is also carrying out military action in Yemen, which has a large Shia Muslim minority.
The current disputes have bubbled for nearly 40 years, since a revolution in Iran in 1979 which saw Shia clerics wrench power from a pro-Western government.
Saudi Arabia swiftly orchestrated the formation of the Gulf Co-Operation Council (GCC), which includes the UAE, Oman, Kuwait, Bahrain and Qatar.
What happens next?
Since then, the Iran wars have seen a Shia government in Iraq, which sits between Saudi Arabia and Iran.
Another flashpoint was the recent Iranian atomic weapons stand-off with the West, which has now been resolved and seen sanctions against the country lifted.
Power, influence and money from the region’s rich oil fields are the real drivers of the disputes between the countries and what happens next is unclear.
The Middle East also splits other world powers.
Russia backs the Shia regime in Teheran, while the US and Europe stands with Saudi Arabia and the GCC nations. Both sides stop at direct conflict because they fear a backlash which could see them lose power and dominance in the region.