US Special Envoy for Yemen Tim Lenderking on Wednesday called on the Houthi rebel group to show more flexibility over an extended and expanded truce deal proposed by the United Nations to build on a previous pact that expired on Sunday. An initial truce first agreed in April had brought the longest stretch of relative calm in the seven-year-old conflict between a military coalition led by Saudi Arabia and the Iran-aligned Houthis. Both sides have been accused of grave violations by human rights groups. Lenderking said in a news briefing that the Houthis, de facto authorities in northern Yemen,…