Amnesty International has released evidence showing that the United States was directly involved in an air strike in Yemen in December that killed fifty-five people, including fourteen women and twenty-one children. Photographs released by Amnesty appear to show parts of a US-manufactured Tomahawk cruise missile that carried cluster munitions. Amnesty said this type of missile is designed to carry a payload of 166 cluster bomblets which each explode into over 200 sharp steel fragments. Neither the USA nor Yemen has yet signed the Convention on Cluster Munitions, a treaty designed to comprehensively ban such weapons. The treaty is due to enter into force in August.