Yemen's Civil War Threatens Global Stability

Yemen's civil war has just gone international, officially. Saudi Arabian jets are now pounding Shia militia bases housing covert agents from Tehran.

This is the latest round in the rapidly evolving regional war between Shia and Sunni .

It threatens to drag most of the Gulf monarchies plus the junta-ruled Egypt into a campaign against Houthi hill tribesmen who have threatened to overrun Yemen, traditionally a Sunni nation.

The Houthis are Zaydi Shia, unlike the Iranian Twelvers - but no matter - they're the new bogeymen of the region.

"What is happening today will change the political geography of the region," said Riad Yassin, Yemen's foreign minister.

"If the Houthis manage to take full control of Yemen and eventually the Iranians will take full control of the region for at least 4,000 years to come."

That is very much the view of most of the Gulf monarchies, most notably the Saudis.

"I think this is more than just an extension of the proxy war," said Firas Abi Ali, chief Middle East analysis at IHS Country Risk.

"I think this is an evolution of the Shia, Sunni conflict in the region from being a proxy region to one that actually involves the sponsor."

In effect the Iranian agenda is to encircle the Saudis and their allies, according to Tehran's critics.

This means creating chaos on Saudi Arabia's borders while Jeddah continues to be part of an international coalition that is fighting Islamic State (IS) to the north.

Iran is also fighting IS, and this week coalition jets were once again in action providing air support for Shia militia and Iranian revolutionary guards during the attack to dislodge IS from Tikrit, Saddam Hussein's home town.

In Syria, Iran backs the Shia regime of Bashar al Assad and the Hezbollah, which is fighting alongside his forces.

Iran has also been accused of fomenting Shia unrest in Bahrain.

Some 15% of Saudis are Shia and the monarchy fears that they could be used in combination with Houthis to destabilise the west of the country while Iran continues its efforts to establish as "Shia crescent" across the Arab Middle East.

But it's not all a Shia conspiracy.

Al Qaeda has a powerful presence in the Yemen, where tribal conflicts and rivalries have usually dominated the sectarian divide.

Which brings us to the role of former president Ali Abdullah Saleh, a Sunni.

Units loyal to him have been fighting in alliance with the Houthi - he managed to rule for three decades and fought three wars against the Houthis.

Now his alliance with them is being seen as one of tactical convenience only.

The aim of internationalising the conflict, though, is to prevent this alliance from gaining any more ground.

Not least because if the Houthis prevail in Yemen, Tehran would have a bridgehead for choking off trade through the Gulf of Aden - much as Iran could throttle oil supplies through the Arabian or Persian Gulf.

Small wonder that Washington is helping in the fight against the Houthis with intelligence and logistics.