AFTER two years of war, a quarter of Yemen’s 28m people are on the brink of starvation. Attention is now turning to Hodeida (pictured), the country’s biggest port, through which the majority of food passes, especially to the rebel-held north where the bulk of the population lives. A military coalition led by Saudi Arabia and backed by Western nations, which sides with the president, Abd Rabbo Mansour Hadi, is finalising plans to invade and take the port. An attack is imminent, say UN observers. A successful raid could push rebel forces—a combination of Shia revivalists, Houthis and soldiers loyal to the former president, Ali Abdullah Saleh—into the mountains and Sana’a, Yemen’s capital. But aid agencies and UN officials warn that fighting over the port would aggravate Yemen’s humanitarian crisis.

Yemen relies on imports for 90% of its food, and even before the war Hodeida handled most of its food trade. The Saudi-led coalition laid siege to the rebel-held port from the moment it entered the war two years ago. Its bombing has badly damaged facilities, disabling the cranes which unload cargo. A Saudi-led effort has stopped the UN from installing replacements (kept in a warehouse in Dubai). As supplies have dwindled, levels of hunger have risen sharply. Shipments resumed partially after a year of fighting, thanks to a UN monitoring mechanism. More than 3.5m tonnes of food and almost 2m tonnes of fuel have since entered rebel-controlled ports. But the UN operates under strict supervision from Saudi, Emirati and Egyptian navies, which say they are enforcing a weapons embargo.

Aid agencies fear that a major assult on Hodeida would cut supply lines to the rebel-held north, including Sana’a. That would be devastating for the two-thirds of Yemenis dependent on food aid. The coalition argues that supplies could instead pass through ports under their control in the south, particularly Aden. Indeed, since Yemen’s southern ports remain under the control of coalition-backed forces and operate freely, that is already beginning to happen. But aid agencies protest that Aden’s current capacity is insufficient to feed the entire country. The road north is also dotted with checkpoints, where armed groups, including al-Qaeda, demand heavy bribes. For the poor, the prices of staples are increasingly beyond reach.

The consequences of a raid on Hodeida will be far-reaching. If the attack fails, the Saudi-led coalition will be humiliated, perhaps to the point of unravelling. A successful assault might see the coalition wrest control of the western coast but it would worsen Yemen’s humanitarian crisis. All sides have already tried to starve their foes into submission, so far to little advantage. Moreover, the loss of Hodeida would deprive the rebels of their main source of income. An assault on Hodeida might not end the fighting, but whatever the outcome it could shift a prolonged stalemate and determine the rest of the war’s trajectory.