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This week, Yemen's already-brutal civil war may be entering an even deadlier and more worrying phase. An Emirati-led offensive is underway against the port city of Hodeida, which is controlled by the Iran-backed Houthi rebels. Security analysts and aid agencies fear that a protracted siege of Hodeida may only deepen Yemen's misery. Hodeida is a crucial hub for humanitarian aid; two-thirds of the Yemeni population depends on food and goods flowing through the port. And urban fighting could put countless civilian lives at risk, displace hundreds of thousands of people and disrupt efforts to alleviate Yemeni suffering.

“It is the lifeline of the country,” said Lise Grande, the top U.N. humanitarian official in Yemen, to my colleagues. “If you cut that port off, we have a catastrophe on our hands.” She predicted that as many as a quarter million Yemenis could die of violence, hunger and illness.

Readers of Today's WorldView will be all too familiar with the grim statistics. Thousands of civilians have died since March 2015. A Saudi-led blockade and the collapse of infrastructure have led to shortages of virtually everything, especially food and medicine. Some 8 million people are on the brink of famine, and more than 1 million have been infected with cholera. By one estimate, around 50,000 Yemeni children died of starvation, malnutrition or disease last year alone.

The Saudis and the Emiratis, the principal foreign powers that intervened on behalf of Yemen's routed government in 2015, argue that aid will move much faster once they have freed the city from the Houthis. Buoyed by key defections in the Houthi ranks, the coalition sees the city's potential capture as the victory that will tilt the war definitively in their favor.

"What most observers fail to understand, after just tuning in to Hodeidah, is that the UAE and its Yemeni partners have been preparing to liberate the port since 2016 to weaken the Houthis, create leverage for negotiators, limit the rebels' ability to import Iranian-provided arms, and bring the port back up to full capacity as a humanitarian import hub," wrote Middle East expert Michael Knights for the National, an Abu Dhabi-based newspaper.

But others in the international community are more skeptical. The Houthis appear primed for a bitter defense of Hodeida that will likely turn into a publicity nightmare for the Saudis and Emiratis as civilian deaths mount. U.N. officials, who administer a weapons-inspection program at the port, are not convinced by arguments that the port has been used to smuggle Iranian weaponry to the Houthis. Even the United States, which is refueling coalition aircraft and supplying it with intelligence and munitions, long cautioned against an outright assault.

“It’s a city with a large number of residents who are not to blame for this war and now find themselves at the front line,” said Frank McManus, the Yemen country director at the International Rescue Committee, to the Wall Street Journal. “Both sides of the conflict have a responsibility to ensure these people are protected.”

The warring parties don't seem committed to that responsibility. "For uprooted villagers, reaching safety has meant crossing front lines, dodging airstrikes and mortar rounds, and traversing roads and fields seeded with land mines," reported my colleague Sudarsan Raghavan. "Villagers have often slipped out of their homes under the cover of darkness to avoid rebels who have been preventing people from fleeing and pressing children to take up arms."

And the intensification of the battle makes the prospect of a negotiated peace less likely. Martin Griffiths, the U.N.'s beleaguered special envoy, has been working fitfully to bring the various factions to the table. "Further military escalation will have serious consequences on the dire humanitarian situation in the country and will have an impact on my efforts to resume political negotiations to reach an inclusive political settlement to the conflict in Yemen,” Griffiths said in a statement earlier this week. “I cannot overemphasize that there is no military solution to the conflict."

The Emirati-led ground offensive on Hodeida began in earnest only after the coalition appeared to get the tacit backing of Secretary of State Mike Pompeo. While U.S. officials are at pains to stress they are not party to the conflict, the Trump administration's top diplomat made a Monday statement on Hodeida that, despite notes of caution, did not warn against attacking the city.

Gregory Johnsen, a resident fellow at the Arabia Foundation in Washington and a former member of a Yemen panel of experts at the U.N. Security Council, suggests that the Trump administration sees eye-to-eye with Riyadh and Abu Dhabi about the need to confront Iran in the Arabian peninsula. Yemen's civil strife did not begin as a regional proxy war. But broader geopolitics now suffuse the country's various fiefdoms and turf wars in a conflict that involves Sudanese mercenaries, UAE commandos and Lebanese Shiite militia Hezbollah.

"The Yemen war is very complicated. There are a lot of different sides and there are alliances that disintegrate overnight and reform seemingly the next day," said Johnsen. He added that the White House may see the current push on Hodeida as a way out of the mess: "The argument that has won the day in the Trump administration is that in order for something to change, [the offensive] seems the best chance to do that now."

But if the worst fears of aid workers are realized and a bloody siege grips Hodeida, it's likely that lawmakers in Congress, as well as foreign governments elsewhere, may force the White House to account for its role in the war.

"Nikki Haley, America’s ambassador to the United Nations, has condemned, rightly, the Syrian government for starving its own people," wrote Alex de Waal of the World Peace Foundation. "But it’s easy to call out villains like President Bashar al-Assad. It’s harder to call out one’s allies — though that may be more effective, and therefore more important."

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