UN special envoy Hans Grundberg started his first visit to Yemen’s rebel-held capital on Monday, following an April 2 ceasefire that the country’s warring parties have accused each other of violating. The Swedish diplomat is scheduled to meet Houthi rebel officials during his first Sanaa visit since taking office in September. “He is looking forward to engaging with Ansar Allah (Houthi) leadership on implementing and strengthening the truce and discussing the way forward,” Grundberg’s office said in a tweet announcing his arrival. The Iran-backed Houthi insurgents took control of Sanaa in 2014…