Airstrikes on Sanaa herald Yemen's emergence as the latest theater for the proxy war between Sunni Saudi Arabia and Shiite-dominated Iran.

The two regional powers have long fought for supremacy, and their competition for power has become perhaps the most defining feature shaping the Middle East's relentless chaos and bloodshed.

Over the years, Tehran's influence spread across a corridor formed by Iraq, Syria, and Lebanon, three countries across the northern rim of the Arab Middle East that have significant Shiite populations. Resentful over a history of discrimination by Sunnis, many Shiites in those countries have been happy to turn to non-Arab Iran.

The sweep of Iranian-allied Shiite rebels over large parts of Yemen, on Saudi Arabia's southern border, now adds to the kingdom's fears it is being encircled by Tehran.

The clash between the two camps has also fired Sunni-Shiite religious hatreds, in turn fueling the growth of Sunni extremist and jihadi groups like al-Qaida and the Islamic State group.

Saudi Arabia and its allies have tried to push back against the Iranian advance — largely unsuccessfully. The decision to intervene with airpower — and maybe more — in Yemen seemed to come suddenly on Wednesday night, but it had been brewing for months.

Egypt and Saudi Arabia are pushing for creation of a regional strike force that could project Arab countries' power in most assertive way in decades. An Arab League summit in Egypt on Saturday is expected to approve the force.

The force is in part aimed at combatting the surge in Sunni Islamic militancy, like the rise of Islamic State group militants in Libya. But Yemen could be another target. Already the region is lining up over the Yemen conflict — Sunni nations from the Gulf, to Jordan to Morocco have backed the strikes; the Shiite-aligned regime in Syria has condemned them.

The West's nuclear negotiations with Iran, now racing into their homestretch, throw another complication. Saudi Arabia and the Gulf worry that a deal will leave Iran on the threshold of being able to build a nuclear weapon — but also that will signal a degree of U.S. consent to Tehran's role in the region.

Here's a look at current flashpoints:


In Saudi Arabia's eyes, the takeover of much of Yemen by Shiite rebels known as Houthis means the creation of an Iranian client in a country the kingdom sees as part of its sphere. The Houthis have overrun Yemen's capital, Sanaa, much of the north and parts of the south, forcing the Saudi- and U.S.-backed president, Abed Rabbo Mansour Hadi, to flee abroad. He re-emerged Thursday in Riyadh, on route to the Arab summit.

Iran insists its backing of the Houthis is purely diplomatic and humanitarian, denying accusations it provides weapons. But there are signs its support goes further. Soon after the Houthis took over the Yemeni capital last year, daily flights were created between Iran and Sanaa, ostensibly to deliver tons of medical supplies. Hadi's government contends that the flights are bringing weapons for the Houthis. In 2013, Yemeni authorities intercepted a ship carrying weapons to Yemen that the United States says is believed to have been sent by Iran to the rebels.

In a speech last month in Tehran, Iranian President Hassan Rouhani made the most overt acknowledgment yet of his country's backing for the Houthis, depicting it as part of a fight against Sunni extremists around the region. "You can see that the power that was able to help the people of Iraq, Syria, Lebanon and Yemen against terrorist group is the Islamic Republic of Iran," he declared. The deputy head of Iran's Revolutionary Guard, Gen. Hossein Salami, compared the Houthis to Iran's client Hezbollah in Lebanon in a January speech.

But Saudi Arabia has its own role in Yemen's current woes. The Houthis' biggest help has come from Yemen's former autocrat, Ali Abdullah Saleh. Saleh was removed after a 2011 uprising, but the Saudi-brokered deal that got him to step down allowed him to remain in the country and keep his loyalists in the military — and those forces are now fighting alongside the Houthis.


Syria's civil war has been the bloodiest and most grueling front in the Iran-Saudi conflict. Saudi Arabia and its Sunni-ruled Gulf neighbors back rebels fighting to topple President Bashar Assad, whose minority Alawite sect is a Shiite offshoot. Tehran has poured money into keeping Assad's government afloat financially, has supplied it with weapons and has backed the intervention of fighters from Lebanon's Shiite militia Hezbollah and from Iraq's Shiite militias on the side of the Syrian military.

For Iran, Syria is a vital ally that gives it influence squarely in the center of the Arab world and a supply route to its military arm in Lebanon, Hezbollah. Saudi Arabia and fellow Gulf nations, along with Turkey, have been determined to see Assad go, aiming to break that foothold.

Instead, the conflict has dragged on for four years with more than 200,000 dead and millions displaced, and has boosted the rise of the Islamic State group, which has seized a third of Syria and Iraq. Now Sunni Arab nations like Jordan and the United Arab Emirates have intervened directly in the conflict — not against Assad but by joining the U.S. in airstrikes against the Islamic State group.


Iran has long been influential in Iraq, but never so much so as over the past year when the Iraqi military collapsed in the face of the Islamic State group. Iran-backed Shiite militias have proved critical to helping the Shiite-led authorities in Iraq fight IS militants. Iran sent Gen. Qassem Soleimani, commander of the powerful Revolutionary Guards Quds Force, to direct operations, along with dozens of military advisers. The U.S. and other allies have launched an air campaign against the militants, even as they keep Iran at arm's length.

The overt Iranian role and the prominence of Shiite militias in the campaign have raised Gulf concerns that Iraq is fast becoming another Iranian satellite state in the region.


With a weak central government and an explosive sectarian mix, Lebanon has always been vulnerable to the pull of Iran and Saudi Arabia backing rival militias. Iran has a proxy in Lebanon's powerful Shiite Hezbollah group, which it arms, funds, trains and guides. This has helped Lebanon's Shiites, who enjoy a plurality over the Sunni Muslims, Christians and the Druse, dominate the country. Saudi Arabia sees itself as the patron of Lebanon's Sunnis and is a main backer of the country's pro-Western, Sunni-led camp.

It is often said in Lebanon that nothing gets done — including electing a president and appointing a prime minister — unless there is an agreement between Saudi Arabia and Iran. The country has been without president for almost a year.


The government of Bahrain has accused Iran of trying to stoke unrest by provoking Bahraini Shiites, who form the country's majority, to overthrow the Sunni-led monarchy. The Shiites deny that, saying their protests aim to bring them greater rights and end their status as second-class citizens. Gulf Arab countries led by Saudi Arabia sent regional forces to Bahrain in 2011 at the height of Arab Spring protests to help quell the protests.