The United Nations mediator for Yemen peace talks said on Friday that four days of discussions had ended with no agreement for even a brief pause in fighting, but that he remained “optimistic,” as aid agencies warned that the humanitarian crisis enveloping the country had worsened. “We feel it requires further consultation and we can achieve it pretty soon,” said the mediator, Ismail Ould Cheikh Ahmed , a Mauritanian diplomat, at a news conference in Geneva, broadcast on the United Nations website. “I remain optimistic.” Yemen has been pummeled by Saudi-led airstrikes since late March, after Houthi rebels from the north drove the sitting president, Abdu Rabbu Mansour […]