Senior Chinese diplomat says dispute with Vietnam can be resolved peacefully

The video features Liu Huchang, the chairman of the Central Research Foundation, who welcomes the audience and discusses the territorial disputes involving China. He emphasizes China's stance on maintaining sovereignty and suggests that Vietnam should be aware of this. Despite the disputes, he believes that both China and Vietnam can resolve their issues through peaceful negotiations and maintain friendly cooperation.

What is the core interest that Liu Huchang mentions regarding China's stance?

What is the overall tone of Liu Huchang's message towards Vietnam?