DUBAI, United Arab Emirates — The world’s worst humanitarian disaster could be about to get even worse. The main port, which millions of Yemenis rely on for food and other supplies, was invaded early Wednesday by a coalition led by Saudi Arabia and the United Arab Emirates
The attack, following several days of failed diplomacy, seemed aimed at tipping the balance in Yemen’s long-running civil war against the Houthi rebels, who control the port, Hudaydah, and armed forces loyal to the Saudis and Emiratis. But any sustained fighting could deepen what is already a catastrophic humanitarian situation.
After years of war, eight million of Yemen’s estimated 28 million people are at risk of starvation, and about a quarter of a million in Hudaydah are in danger of injury or death if urban assault intensifies, according to the United Nations and aid agencies.
“This attack risks more people dying, but it also risks cutting the lifeline of millions of Yemenis,” said Jolien Veldwijk, the acting country director in Yemen for the aid agency Care International. “Food imports already reached the lowest levels since the conflict started, and the price of basic commodities has risen by a third. We are gravely concerned that parts of the population could experience famine.”
The Saudis and Emiratis intervened in the war three years ago with hopes of a quick victory over the Houthis, who they say are backed by Iran. Instead, the two nations have been stuck in a quagmire. With the assault on Hudaydah, they apparently hope for a symbolic victory over the group that would give the Arab neighbors an upper hand in peace negotiations. The Houthis still control the capital, as well as territories in northern Yemen, their ancestral lands.
American military officials, including Defense Secretary Jim Mattis, are wary of the assault and have warned their Arab allies that it could end in failure both militarily and politically, and result in further civilian suffering.
Yemeni troops, trained and funded by the United Arab Emirates, led Wednesday’s ground offensive, which began around daybreak. Airstrikes launched by the coalition concentrated on two pro-Houthi neighborhoods on the southern outskirts of town, according to residents.
Aid workers who have remained in Hudaydah said the center of the city remained mostly quiet.
Two diplomats familiar with the situation said that the Saudi-Emirati coalition aimed to seize the port facilities, but by late afternoon that planned assault did not appear to have started.
The United Nations, meanwhile, was frantically trying to unload two shiploads of food aid before the anticipated hostilities broke out. The organization’s officials were also setting up distribution hubs of emergency relief and food packets in the event of large civilian evacuations from the city.
The Hudaydah operation began while Washington’s attention was still focused on the summit meeting between President Trump and North Korea’s leader, Kim Jong-un. It was not immediately clear what role, if any, American military advisers would play in the campaign. The New York Times reported last month that United States Army commandos were helping to locate and destroy caches of ballistic missiles and launch sites that Houthi rebels were using to attack Saudi cities.
Since 2015, the United States has provided the Saudi-led air campaign in Yemen with air-to-air refueling, intelligence assessments and other military advice, but even those roles have been contentious.
The Pentagon insists that all of its military aid is noncombat assistance, like advising the Saudi Air Force on adopting bombing practices that kill fewer civilians. But at the same time, the defense contractor Raytheon is courting lawmakers and the State Department to allow it to sell 60,000 precision-guided munitions to the Saudis and Emiratis, in deals worth billions of dollars.
American advisers do not give direct or indirect approval on target selection or execution of bombings against Houthi rebels, Pentagon officials say. Rather, they give advice on targeting procedures and facilitate checks of a list of “no-strike” buildings, like mosques and marketplaces.
“It’s providing any intel, or anything we can give to show no-fire areas where there are civilians, where there’s mosques, hospitals, that sort of thing,” Mr. Mattis, the defense secretary, told reporters at the Pentagon on Monday, when asked about American support to the impending offensive.
Maj. Adrian J. Rankine-Galloway, a Pentagon spokesman, said on Wednesday that these intelligence-sharing procedures had not changed in the prelude to the offensive, and that the United States was not providing specific information on Houthi targets for Saudi Arabia or the United Arab Emirates.
An increasing number of Republican and Democratic lawmakers in Congress are criticizing even this limited role, accusing the Pentagon of being complicit in the errant bombing campaign.
In one testy exchange at a Senate Armed Services Committee hearing in March, those tensions boiled over.
“We are enabling the Saudis to continue their battle there,” said Senator Mazie K. Hirono, Democrat of Hawaii.
“We’re not parties to this conflict,” replied Gen. Joseph L. Votel, the head of the Pentagon’s Central Command, which oversees operations in the Middle East.
“We’re helping them,” Ms. Hirono shot back. “We’re enabling the Saudis.”
Nine Senate Republicans and Democrats wrote to Mr. Mattis and Secretary of State Mike Pompeo on Tuesday, expressing “grave alarm” that the impending offensive would worsen the humanitarian crisis in the country.
Yemen’s civil war began in 2015, in the wake of Arab Spring protests that toppled the country’s longtime autocratic president, Ali Abdullah Saleh. Divisions over power sharing gave way to military conflict, and competing forces now hold divided areas of the country.
The Houthis, who are from northern Yemen and represent one of the country’s major political constituencies, swept south three years ago and seized control of the capital, Sana. Soon after, they stormed Hudaydah. The internationally recognized president is now in exile in Saudi Arabia.
Riyadh and Abu Dhabi intervened militarily, funding and training Yemeni forces opposing the Houthis, whom they consider to be a proxy for their regional nemesis, Iran.
Most Yemeni analysts and diplomats view the war as a battle of political supremacy, not religion. The Houthis, as well as several other Yemeni factions, are Shia, but a sect indigenous to their country and different from that followed by most Iranians.
The Saudis and Emiratis claim the Houthi rebels have been smuggling arms through the port of Hudaydah, including missiles used to attack Saudi Arabia.
A United Nations team of monitors said in a recent report on Yemen that their findings did not support those allegations, concluding that it was more likely that weapons were being smuggled across land borders.
The Houthis claim that their actions are legitimate self-defense against foreign aggressors. The Saudis, who have spent decades intervening in Yemeni politics, view the Iran-backed Houthis as a threat on their southern border.
Earlier in the week, American officials repeated their warning about an assault on Hudaydah to the Emiratis.
Secretary of State Mike Pompeo said he had spoken to Emirati leaders “and made clear our desire to address their security concerns while preserving the free flow of humanitarian aid and lifesaving commercial imports.”
He said the United States expected “all parties” to work with the United Nations special envoy for Yemen and to “support a political process to resolve this conflict.”
But in the past few days, it appeared American officials were resigned to the offensive going forward, and began focusing on ensuring that an assault did worsen conditions on the ground.
“That all sounds to me like ‘If you must do it, please do it carefully,’ which is notable for the absence of any expression of concern regarding the consequences of an assault, either on the operations of the port or the city’s civilian population,” said Stephen A. Seche, a former United States ambassador to Yemen. “So, the red light certainly has shifted to yellow.”