When a civil war in Yemen erupted more than three years ago, it fractured what was already the poorest Arab nation and eventually plunged it into the planet’s worst humanitarian disaster.
While the world has turned its gaze from the prolonged conflict, it has grinded on without easing and grown increasingly complex.
An assault by the Saudi-led coalition that has been battling Iran-backed Yemeni rebels for more than three years began Wednesday on the city of Al Hudaydah, which has a port that serves as a vital supply route for humanitarian aid and other vital supplies to the bulk of Yemen’s population. It marked the latest turn in a situation moving toward catastrophe for millions of civilians.
The war has already killed thousands of civilians and left three million people internally displaced.
Who are the main parties to the conflict?
The conflict began as a fight between armed Houthi rebels from the north of the country and the government, then led by President Abdu Rabbu Mansour Hadi. The Houthis are part of the Shiite Muslim minority in Yemen.
Saudi Arabia and its neighbor and close ally, the United Arab Emirates, intervened in 2015 because of perceived Iranian support for the rebels. The Sunni Muslim monarchy of Saudi Arabia and Shiite Iran are rivals for power and influence across the Middle East, and Yemen has become a battlefield for one of the proxy wars between them.
Iran has denied supporting the Houthis, but Iranian-made missile have been used by the group during the war.
Still, Yemen’s war stems more from a dispute about national political influence than sectarian conflict, analysts say.
The conflict has carved the country up into Houthi-controlled zones in much of the northeast, including the capital, Sana, and large parts of the south and west controlled by pro-government Saudi-led coalition forces.
How did Yemen’s conflict reach this point?
The conflict has its roots in Yemen’s Arab Spring uprising that began in 2011 and forced the longtime authoritarian president, Ali Abdullah Saleh, an ally of the United States, from power. Though Mr. Saleh had led a unified Yemen since the 1990s, competing interests loosened his grip on the nation. Al Qaeda in the Arabian Peninsula (AQAP), one of the most potent offshoots of the global terrorist network, thrived in large parts of the country, and Houthi rebels gained power in the north.
Then, months after the Arab Spring protests began, Mr. Saleh handed leadership of Yemen to his deputy, Mr. Hadi, and stepped down. But Mr. Hadi struggled to control a nation already deeply divided, and Mr. Saleh continued to wield power by aligning with the Houthis.
By 2014, the Houthis and their supporters — including sections of the Yemeni military loyal to the Mr. Saleh — stormed the capital and forced Mr. Hadi and his internationally recognized government into exile in Saudi Arabia.
Saudi Arabia and several allied Arab states including the United Arab Emirates, intervened in 2015. Backed by the United States and Western allies, they launched airstrikes on Houthi forces and drastically escalated the conflict. The Houthis responded by firing missiles into Saudi territory.
Civilians, mostly those in Houthi areas, were increasingly caught in the crossfire. Then Mr. Saleh, the former president, was killed by Houthis late last year after he abruptly abandoned the alliance with them.
What is the importance of Al Hudaydah?
For millions under Houthi control, the Red Sea port of Al Hudaydah is the only supply route for humanitarian aid — including food and medicine — and other vital supplies. An estimated two-thirds of the population relies on it.
The city is home to about 400,000 people, and with just two main routes in and out, a prolonged siege could leave hundreds of thousands cut off, unable to flee. Many aid groups pulled staff members out of the city in anticipation of the battle.
Wednesday’s offensive was carried out by Yemeni troops, trained and funded by the United Arab Emirates. Both the Emiratis and the Saudis have accused the Houthis of using the city to smuggle Iranian weapons into Yemen. United Nations monitors say it’s unlikely that weapons are being smuggled through Red Sea ports, and are most likely coming across land borders.
A humanitarian crisis threatens to worsen.
The United Nations and aid agencies have warned that an attack on Al Hudaydah could exacerbate an already out-of-control humanitarian crisis and called for a cease-fire.
“They must act now to secure a cease-fire before the people in Hodeidah city suffer the same fate as those in Aleppo, Mosul or Raqqa,” David Miliband, the president and chief executive officer of the International Rescue Committee, said in an email statement, likening the potential outcome to long-term sieges in Syria and Iraq.
Relentless airstrikes have already shattered the infrastructure in many Houthi-controlled areas, with bombings damaging hospitals and sewage facilities.
Preventable diseases have run rampant. A 2017 cholera epidemic in Yemen was the largest and fastest outbreak of the disease on record. The United Nations has said both the Saudi-led coalition and the Houthis have carried out actions that could amount to war crimes, and both sides have been accused of intentionally targeting dozens of hospitals and health care facilities as well as civilian centers.
Even before the most recent offensive, millions of Yemenis were teetering on the brink of famine, with an estimated 60 percent of the population of 29.3 million categorized as food insecure, according to the World Food Program.
The International Committee of the Red Cross said that it had stockpiled food, medicine and water purification systems in the area in anticipation of the battle, but that the aid could not be distributed while fighting is underway.
“Real people, real families, will suffer if no food is getting in, and we are concerned that ongoing military operations continue to hamper the arrival of essential goods,” said Robert Mardini, the regional director the International Committee of the Red Cross.
Additional reporting by Troy Griggs.