Russia's deepening military relationship with North Korea raises concerns for China, especially amid delays in the Siberia 2 gas pipeline. Fearing North Korea's access to Russian weapons technology, China worries about regional stability and its strategic balance against US forces in South Korea. US-China talks on North Korea's weapons program underscore America's push for Chinese intervention. China seeks clarity on Russia-North Korea ties but faces challenges in pipeline negotiations, potentially straining Sino-Russian relations.