Oil prices fell slightly on Thursday as rising U.S. crude inventories due to robust shale production outweighed concerns over renewed air strikes in Yemen. Saudi-led coalition warplanes continued bombing Yemen on Wednesday despite an announcement by Riyadh a day earlier that it was ending its campaign of air strikes. While Yemen is not among the biggest producers in the Middle East, others in the region ship crude bound for Europe along the Gulf of Aden on Yemen’s southern coast and through the narrow straits of Bab el-Mandeb, between Yemen and Djibouti.