Updated on March 25, 2015 at 8:15 p.m.
On Wednesday evening, the Saudi ambassador to the United States announced that his country had initiated airstrikes against the Houthi rebels in Yemen:
Amb: "KSA launches military operations in Yemen with coalition of over 10 countries in response to request from the legitimate Yemen gov."— Saudi Embassy (@SaudiEmbassyUSA) March 25, 2015
U.S. officials have since confirmed the development.
In recent days, before his whereabouts became unknown (see below), the embattled Yemeni President Abd-Rabbu Mansour Hadi had called on the United Nations to authorize a military intervention by "willing countries that wish to help Yemen" against the Houthi advance.
Those "willing countries" are led by Saudi Arabia, which didn't disclose the other nine countries in its coalition on Wednesday. It's a safe bet that many of them are from states in the Gulf Cooperation Council as well as Egypt, which has been vocal about a possible intervention in Yemen.
Given Iran's connection to the rebels, it's unclear how this escalation might play out. As one analyst noted on Twitter, there's an irony to Saudi Arabia targeting Iran-backed forces in Yemen while American airstrikes aid Iran-backed forces in Iraq.
On Wednesday, the Associated Press relayed reports from officials in Yemen that President Abd-Rabbu Mansour Hadi, the country's internationally recognized leader, had "fled the country by sea ... on a boat from Aden." Meanwhile, quoting a "senior Yemeni official," Richard Engel of NBC News countered on Twitter that the president is still in the country.
A Slow-Motion Coup
Earlier this year, Iran-linked Houthi rebels took control of Sanaa, Yemen's capital, after a months-long standoff. President Hadi, who was placed under house arrest in Sanaa last month, then fled to Aden, a port city and economic hub. In the past few days, the Houthis have surrounded Aden and seized the city's airport as well as al-Anad, a government air base and launch pad for American drones.
The Battle for Control of Yemen
The Warring Factions
In addition to government forces loyal to Hadi and the Houthis, there are other factions helping the Houthis who still support former Yemeni President Ali Abdullah Saleh, which, as analyst Gregory Johnsen explains, is ironic given the "bloody history" between Saleh and the Houthis. In recent days, the U.S. State Department has called on Saleh to stop inciting violence against Hadi's tenuous rule.
Making matters more complicated, Yemen is also home to al-Qaeda's powerful Yemeni branch, which the United States has assiduously (and controversially) targeted with drones over the past several years.
Last week, a terrorist group calling itself the Yemeni affiliate of the Islamic State carried out dual suicide attacks at mosques in Sanaa, which killed over 130 people. While the United States and others cast doubt on the group's links to ISIS, the attacks (which al-Qaeda denounced) stoked fears of a burgeoning Islamic State presence in Yemen. Shortly after Friday's attack, the State Department pulled all of its personnel from the country.
The Role of Iran and Saudi Arabia
All of this violence is occurring within a larger regional frame in which arch-rivals Iran and Saudi Arabia are sparring over their interests in Yemen.
"Yemen's slide towards civil war has made the country a crucial front in mostly Sunni Saudi Arabia's rivalry with Shi'ite Iran, which Riyadh accuses of stirring up sectarian strife through its support for the Houthis," who are Shiite, Reuters noted.
On Tuesday, American officials said that Saudi Arabia had positioned heavy artillery near its border with Yemen, although the Saudis claim the build-up is "defensive."