The United Nations humanitarian branch is warning that 13 million people in civil-war-torn Yemen are facing starvation.

UN advocates are calling on a military coalition led by U.S. ally Saudi Arabia to halt air strikes that are at times missing targets and killing civilians, while decimating villages. The action is contributing to what the UN says could become “the worst famine in the world in 100 years.” Disease, including the diphtheria that this young Yemeni girl suffers from (eradicated by immunization in much of the West), is another challenge for humanitarian efforts.

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Lise Grande, the UN’s humanitarian coordinator in Yemen, says the magnitude of the crisis may be just now sinking in: “I think many of us felt as we went into the 21st century that it was unthinkable that we could see a famine like we saw in Ethiopia, that we saw in Bengal, that we saw in parts of the Soviet Union — that was just unacceptable,” she told the BBC. “Many of us had the confidence that would never happen again, and yet the reality is that in Yemen that is precisely what we are looking at.”

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Already impoverished Yemen’s civil war began three years ago, when Houthi rebels, backed by Iran, took over much of the country, including the capital city, Sanaa. At least 10,000 civilians have been killed and millions displaced.

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Saudi Arabia, backed by the U.S., the U.K. and France, is using air strikes and a blockade of goods, including food, as it supports Yemen’s internationally recognized government against the Iran-backed rebels. Yet the West’s relationship with Saudi Arabia has entered a new phase after the alleged murder earlier this month of Saudi journalist and U.S. resident Jamal Khashoggi inside the kingdom’s consulate in Istanbul. Saudi Arabia, after weeks of delay, has now confirmed the journalist’s death, widely reported to have included torture and dismemberment.

Here, U.S. Secretary of State Mike Pompeo sits with Saudi Crown Prince Mohammed bin Salman on Oct. 16 in what appeared to be a largely congenial meeting. The visit drew some criticism after the Trump administration defended the importance of a U.S. arms deal with the oil-rich Mideast stronghold Saudi Arabia in spite of the murder allegations. Pompeo, according to CNN, told the prince he had to “own” the Khashoggi situation. Opinion: Why Trump has to play the Saudis’ game — for now

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Yemeni women work in a sparse vegetable field in the northern district of Abs in Hajjah Province this month.

The UN has already received one of the biggest donations for relief in aid history: $930 million to its Yemen Humanitarian Fund. Among the biggest contributors? Saudi Arabia and the United Arab Emirates, two countries that have helped fuel Yemen’s conflict. UN Secretary-General António Guterres has expressed his “deep gratitude” to MBS, as the Saudi crown prince is known, but he called for the kingdom to abide by the rules of war and lift the blockade on Yemen’s ports, which is choking off food sources.

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Yemeni children accompanied by their fathers hold weapons during a September gathering in Sanaa, the capital city, to show support for the Houthi Shiite movement against the Saudi-led intervention.

Saudi Arabia’s ambassador to the UN’s European headquarters in Geneva, Abdul Aziz Al-Wasel, said that the kingdom had written to the UN High Commission with its criticisms of the global organization’s speaking out against Saudi action in the war, arguing that the organization’s recent findings did not include reports that Iranian-backed Houthi militias detained and looted vessels carrying aid, Arab News reported.

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Beyond mere survival, 2 million children across Yemen have no access to education, according to the UN children's agency UNICEF. Here, children attend class this month in a house turned into a makeshift school in the southwestern city of Taez.

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Civil war is the large driver of this crisis, but Yemen’s struggles highlight food inequity elsewhere. For example, a New York resident could spend $1.20 on a simple home-cooked meal like a bean stew, representing just 0.6% of the average daily income, UN researchers have found. In Yemen that cost is the equivalent to $62 for a bowl of stew. And by comparison, in South Sudan, the same dish would cost twice the average daily income — the equivalent of a U.S. citizen spending $348, UN researchers found.