He also blamed the Houthis.
“The people of Yemen are being subjected to deprivation, disease and death as the world watches,” he said.
Mr. O’Brien also implored the Saudis to avoid an attack on Hodeidah, the only port in Yemen that can still handle shiploads of food and medicine. Virtually all of the basic needs in Yemen, the Arab world’s poorest country, must be imported.
Saudi Arabia and its Arab allies have vowed to crush the Houthis, seeing them as proxies for Iran’s influence in the region. The Saudis have pledged to retake all territory seized by the Houthis, who are from the north of Yemen, and reinstate the Saudi-backed government that was forced to flee the capital, Sana, in 2015.
Although widely criticized for indiscriminate bombings in Yemen, the Saudis have also suggested they are in no rush to end a war that has ravaged their neighbor, leaving roughly 10,000 Yemenis dead and millions destitute and at risk of disease.
Mohammed bin Salman, the deputy crown prince and defense minister of Saudi Arabia, said in a televised interview on May 2 that his side could just exhaust the Houthis and starve them of supplies.
Last week, the Saudis received a strong signal of American support when President Trump visited Saudi Arabia and signed a $110 billion weapons deal, including warplanes and armaments that could presumably be deployed in the Yemen conflict.
For Mr. O’Brien and other international aid advocates, the conflict has become the world’s largest food security crisis, which has now been aggravated by a fast-spreading cholera outbreak.
Less than a month ago, the World Health Organization reported nearly 800 cases and at least 34 deaths from cholera, which causes fatal dehydration from water contaminated by feces.
On Tuesday, Mr. O’Brien and other United Nations officials said the…