SHANGHAI Party Secretary Han Zheng met Dang Minh Khoi, Vietnamese ambassador to China, last week. Han said the two countries have a long and traditional relationship. Last year, Chinese President Xi Jinping and Vietnamese Communist Party general secretary Nguyen Phu Trong visited each other’s country to set a path for future cooperation between the two countries. He noted that Shanghai and Ho Chi Minh City have cooperated well in economy, trade, science and technology, education and culture after they became sister cities 20 years ago.