The United Nations on Saturday voiced concern that regional tensions involving Yemen could adversely affect efforts to end a years-long civil war in the country. The United States and its allies this week launched a series of strikes targeting Yemen’s Houthi rebels after they had repeatedly attacked commercial ships in the Red Sea. UN special envoy for Yemen Hans Grundberg said he had noted “with serious concern the increasingly precarious regional context, and its adverse impact on peace efforts in Yemen.” He stressed “the need to protect Yemeni civilians, and to safeguard the progress of pea…