The United Nations has asked for $2.1 billion to help Yemen where millions of people are caught in a two-year-old civil war. A Saudi Arabian-led coalition began bombing in the Middle Eastern country two years ago. The attacks are in support of the Yemeni government as it battles against a group of rebels called Houthis. U.N. officials said the air strikes have destroyed bridges, major roads, entire neighborhoods and a port. This has left millions of people without electricity, safe water or food. Stephen O’Brien is the under-secretary-general for humanitarian affairs and emergency relief coordinator for the U.N. He said 18.8 million people, or two-thirds of Yemen’s population, need humanitarian aid.