North Korean leader Kim Jong-un and Chinese President Xi Jinping have reiterated their shared commitment to strengthening strategic cooperation between the two countries in their messages marking the 65th anniversary of the signing of a friendship treaty, Pyongyang's state media said Saturday. The leaders exchanged the messages, pointing to the shifting international security situation, the Korean Central News Agency reported, as a Sino-U.S. rivalry is intensifying, with Seoul, Washington and Tokyo continuing to reinforce cooperation in confronting shared challenges. The exchange followed their summit talks in Pyongyang last month, which came at a time when Beijing was seen striving to improve relations with North Korea, which has drawn closer to Russia through deepening military, diplomatic and economic cooperation. In his missive, Kim highlighted his readiness to develop the bilateral relationship into a "model of the most powerful and strategic relations" between socialist countries by guiding it to a "new height," together with the Chinese president. "The DPRK-China friendly and coop