North Korean leader Kim Jong Un observed sea trials of a new warship repaired after a failed launch last year and vowed to accelerate efforts to build a nuclear-armed navy, state media said Saturday, showcasing his expanding military capabilities ahead of a visit by Chinese leader Xi Jinping. North Korea’s official Korean Central News Agency said Kim visited the 5,000-ton destroyer Kang Kon on Thursday as it underwent capability tests. Photos released by the agency showed him accompanied by his