At any moment, Saudi Arabian troops could march through Yemen, heating up an already intense conflict that could have ramifications across the Middle East.
Saudi Arabia and eight other countries are striking a common enemy from the air: Shiite Houthi rebels, who have captured key parts of Yemen, ousted that country’s President and could spread Iran’s influence in the region.
The establishment of an Iranian proxy power in Yemen is an unacceptable notion to Iran’s bitter rival on the Persian Gulf, Saudi Arabia, as it is to Israel’s government.
Already home to militants from al Qaeda in the Arabian Peninsula, Yemen now teeters on the brink of becoming a failed state and even more fertile breeding ground for extremism.
But if the coalition takes the fight to the ground, the cost could be intense. Houthis are battle hardened guerrilla fighters and could cross into Saudi Arabia.
Here’s the latest on the battle in Yemen and how it affects the world:
The airstrikes
Saudi-led airstrikes targeted Houthi military posts and weapons depots in the capital city of Sanaa on Monday, two Houthi commanders told CNN.
No details of casualties have been reported.
Previously, airstrikes hit Houthi militant groups, smashed their big air defense guns and crumbled key infrastructure that links major towns with Sanaa, a Saudi official has said.
The Saudi-led effort has been dubbed operation al-Hazm Storm. The Arabic term “al-Hazm” can be translated as “determinant” or “decisive.”
Saudi Arabia and Egypt have both talked about the possibility of putting boots on the ground. On Saturday, Yemeni Foreign Minister Riyadh Yaseen said he expected coalition troops to be in Yemen within days.
The players
The conflict splits the region along religious lines. Decisive Storm’s coalition includes the majority Sunni nations of Saudi Arabia, the United Arab Emirates, Kuwait, Bahrain, Qatar, Jordan, Morocco, Egypt and Sudan.
The Shiite Houthis are allied with Iran, a majority Shiite nation. Saudi Arabia has accused Iran of beefing up the Houthis’ weaponry for their offensive.
Iran has sharply denounced the Saudi-dominated armed intervention.
On Sunday, Israeli Prime Minister Benjamin Netanyahu accused Iran of trying to use the conflict in Yemen to “take over the whole Middle East.”
The United States has voiced approval of the airstrikes and is supporting the coalition logistically. While it is helping the Saudi-led team in locating targets, the U.S. is not participating in active battle.
The damage
Dozens have died in the strikes, Houthi commanders said.
Rebel commanders also said the coalition struck the Houthi-controlled al Anad Airbase, which was used as the headquarters for U.S. counterterrorism operations before Houthi rebels took control of it.
The Houthis also claimed to have shot down a Sudanese jet and captured the pilot on Saturday. They distributed photos of a pilot and wreckage to back up the claim.
The backstory
The Yemeni crisis erupted when Shiite Houthi rebels, who have long felt marginalized in the majority Sunni country, began seizing control of the capital and other areas of the country last fall.
Houthis moved into Sanaa in September, sparking battles that killed a few hundred people before a ceasefire was called.
The President
Yemeni President Abdu Rabu Mansour Hadi fled the capital over a month ago.
In January, Houthis surrounded the presidential palace. Hadi resigned and was put under house arrest.
Hadi escaped in February and went to the city of Aden, but declared he was still the country’s leader.
Last week, Hadi went to Sharm el-Sheikh, Egypt, to attend the Arab League summit, where he is rallying support with leaders of member nations for operation Determination Storm.
Even from afar, Hadi had strong words for the Houthis on Saturday:
“You violated the sovereignty (of Yemen), and you bear the responsibility for what happened and what is going to happen.”
The global effect
Many U.N. representatives have had to flee the chaos. And Saudi naval special forces have rescued dozens of diplomats, a Saudi official has said.
The conflict in Yemen also led to the withdrawal of U.S. special forces earlier this month, seriously undermining counterterrorism efforts in a country that has been a stronghold for al Qaeda in the Arabian Peninsula.