I agree in general with all you say. However, there has been in the past border issues between Russia and China. These are land conflicts and China has a long history of remembering the past. Their current cooperation suits them in the current climate but don't count on them having long term friendship. Nations in conflict are always about acquiring resources, cultural and national glory and exploiting defeated countries. Poor and uneducated people are always attracted to the promises of hope, glory and opportunity. Conflict diverts attention away from internal issues and it's always easier to move soldiers by land than sea. Land boundaries offer more opportunities and are much cheaper than sea mounted ones in times of conflict in my opinion.
