Who is fighting in Hodeidah and why?

The port city has been controlled by Yemen’s Houthi rebels since 2015. It is an important commercial centre, but since the war broke out, Hodeidah has become Yemen’s aid lifeline.

The new assault by the Arab coalition that backs Yemen’s exiled government has been a long time coming.

It involves three different Yemeni factions allied with the government, as well as Saudi and UAE forces. At least 2,000 troops are on the city’s outskirts and coalition airstrikes have begun.

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The coalition hopes that retaking the city could potentially open a pathway to finally retaking the capital of Sanaa from the rebels.

Why are the UN and aid agencies sounding the alarm?

Almost 80 per cent of Yemen’s imports, including much of its food, flowed through Hodeidah even before the war broke out in 2015.

The port is basically now the country’s only aid and goods pipeline thanks to a Saudi-led blockade of Yemen’s borders and air space – so any damage to it could cut off crucially needed supplies.

A staggering two-thirds of Yemen’s 28-million-strong population is dependent on aid to survive, and 8 million of those are food insecure.

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“Yemen is on the precipice of a full scale famine. A major attack on Hodeidah could act as the catalyst for that,” Save the Children’s CEO, Kevin Watkins, told The Independent.

“We and other agencies are doing what we can but the scale of need in Yemen is already beyond our capabilities.”

What happens next?

Hodeidah will be the biggest battle in Yemen’s three-year-old war to date, and the first that could involve sustained urban warfare – which inflicts heavy casualties on both fighting forces and civilians.

The United Nations warned last week up to 250,000 of the city’s 600,000 residents were in danger.

The Houthis have heavily mined the town and surrounding areas, which will slow the coalition’s progress.

It is hoped the rebels will capitulate quickly and retreat to the surrounding mountains, but there have been promises to give government forces “hell on hell” before doing so.

To date, coalition bombing in the country has managed to indiscriminately hit civilian infrastructure. Many observers are worried Hodeidah will suffer more of the same.

Is there any chance the fighting can be avoided?

The UN’s special envoy to Yemen, Martin Griffiths, is still trying to broker a deal with both sides to at least make sure the port is put under neutral UN jurisdiction during any fighting.

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While talks are on going, Saudi state news announced in the early hours of Wednesday that a 48-hour negotiating period had expired and the offensive was underway.

Several actors have warned that the offensive could derail overall peace talks and render short-term military gains ineffective.

While the US state department has always vociferously warned against an assault on Hodeidah, in recent weeks the line appears to have softened.