North Korean Premier Pak Thae-song has vowed efforts to expand bilateral ties with China in a thank-you message to Chinese Premier Li Qiang, as he has returned home after a three-day trip to China for a key treaty anniversary, state media reported Monday. A North Korean delegation led by Premier Pak returned to Pyongyang the previous day from China, where he attended an event to mark the 65th anniversary of the signing of the two country's friendship treaty, according to the Korean Central News Agency (KCNA). In a thank-you note to Chinese Premier Li for "sincere hospitality," Pak wrote North Korea was willing to work with "the Chinese comrades to comprehensively expand and develop the traditional DPRK-China friendly and cooperative relations as required by the new era true to the noble intention of the top leaders of the DPRK and China," the KCNA reported. DPRK stands for North Korea's official name, the Democratic People's Republic of Korea. During his visit, Pak met with Chinese President Xi Jinping, his counterpart Li and other high-ranking officials, including Cai Qi, director of th