We write as scholars concerned with Yemen and as residents/nationals of the United Kingdom and the United States. The military attack by Saudi Arabia, backed by the Gulf Cooperation Council states (but not Oman), Egypt, Jordan, Sudan, the UK and above all the US, is into its third week of bombing and blockading Yemen. This military campaign is illegal under international law: None of these states has a case for self-defense. The targets of the campaign include schools, homes, refugee camps, water systems, grain stores and food industries. This has the potential for appalling harm to ordinary Yemenis as almost no food or medicine can enter. Yemen is the poorest country of the Arab world in per capita income, yet rich in cultural plurality and democratic tradition. Rather than contributing to the destruction of the country, the US and UK should support a UN Security Council resolution demanding an immediate, unconditional ceasefire and use their diplomatic influence to strengthen the sovereignty and self-government of Yemen.