SEOUL, South Korea (AP) — The leaders of China and North Korea are reaffirming their traditional alliance following contentious talks between top diplomats from Washington and Beijing and ongoing diplomatic isolation and economic problems in the North that have left it ever-more dependent on the Chinese. The North’s state media said leader Kim Jong Un called for stronger “unity and cooperation” with China in the face of challenges posed by “hostile forces” while exchanging messages with Chinese President Xi Jinping. Xi in his own message to Kim described bilateral relations as a “valuable asset” to both countries and vowed to contribute to peace on the Korean Peninsula.