A Saudi-led alliance of Arab states launched the largest assault of Yemen's war yesterday with an attack on the main port city, aiming to drive the ruling Houthi movement to its knees at the risk of worsening the world's biggest humanitarian crisis.
Arab warplanes and warships pounded Houthi fortifications to support ground operations by foreign and Yemeni troops massed south of the port of Hodeidah in operation "Golden Victory".
The assault marks the first time the Arab states have tried to capture such a heavily-defended major city since they joined the war three years ago against the Iran-aligned Houthis, who control the capital Sanaa and most of the populated areas.
The Houthis had deployed military vehicles and troops in the city centre and near the port, as coalition warplanes flew overhead striking a coastal strip to the south, one resident, speaking on condition of anonymity, told Reuters. People were fleeing by routes out to the north and west.
CARE International, one of the few aid organisations still operating in Hodeidah, said 30 air strikes had hit the city within half an hour yesterday morning.
"Some civilians are entrapped, others forced from their homes. We thought it could not get any worse, but unfortunately we were wrong," said CARE acting country director, Jolien Veldwijk.
Saudi-owned Al Arabiya TV quoted witnesses describing "concentrated and intense" bombing near the port itself.
The United Nations fears the assault could drastically worsen already desperate conditions in the region's poorest country. The city and surrounding area are home to 600,000 people, and the port is the main route for food and aid to reach most Yemenis, 8.4 million of whom are on the verge of famine.
UN refugee chief Filippo Grandi said there was a danger of a more immediate crisis if Yemenis began to abandon their homes in large numbers.
Western countries, particularly US and Britain, have quietly backed the Arab states diplomatically and sell them billions of dollars a year in arms, but have mostly avoided direct public involvement so far in the Yemen conflict. A major battle could test that support, especially if many civilians are killed or supplies disrupted.
The operation began after the passing of a three-day deadline set by the United Arab Emirates, one of the coalition's leaders, for the Houthis to quit the port.
With its military intervention in Yemen, the alliance aims to restore the government of President Abd-Rabbu Mansour Hadi, who was driven from Sanaa and into exile in 2014.
Yemen has been in crisis since 2011 mass protests that ended the 33-year rule of Saleh. A Saudi-brokered transition brought Hadi to power in a government that sidelined the Houthis, who become disgruntled and captured much of the country.
For a time Saleh joined forces with the Houthis, although they turned on each other last year and Saleh was killed. Parts of Yemen are also held by al Qaeda and Islamic State militants.
Yemen lies beside the southern mouth of the Red Sea, one of the world's most important trade routes, where oil tankers pass from the Middle East through the Suez Canal to Europe.