China-US relations have become the focus of world attention after the Biden administration took power. Some predict that Biden‘s strategy in the early days of his administration will be a combination of Obama’s and Trump‘s Policies toward China, which focus on competition rather than reconciliation and cooperation. Biden stated clearly that he has no intention to involve in a“new cold war”with China, he will not deliberately exclude engagement with China, he also has proposed that intensive cooperation with China will be put into effect on the theme related to climate change, global public health and nuclear non - proliferation. Meanwhile, the Biden administration continues to claim that China is the Unites States’ “most rigorous competitor”. The US government will carry out a series of strategic policy in the areas of economy, security, diplomacy, human rights, intellectual property, and global governance. the Biden administration continued to promote the Indo-Pacific strategy more actively in order to achieve the upgrading of the four-country dialogue mechanism with Japan, India and Australia and also make great effort to strengthened the relationship of traditional Allies, by which achieving the goal of containing China. With the framework of the “One China” policy, the Biden administration intend to strengthen unofficial relations and non-government contact with Taiwan to improve Taiwan‘s self-defense capability and international visibility aim to maintain the status quo of“no independence”and“no unification”between Taiwan and the mainland. For the foreseeable future, Biden will inherit the tone of the Trump administration‘s strategic competition toward China through some necessary political adjustment. the China-US relations will be imbued with challenge and opportunities.

Based on the system and field of international exchange and cooperation between local governments after the establishment of diplomatic relations between China and South Korea, this paper analyzes the characteristics and future issues of international exchange and cooperation between local governments of China and South Korea. The main achievements of bilateral cooperation are as follows: First, sister cities of friendship between the two sides have developed rapidly. Local government cooperation has both the characteristics of "transborder regional parallel diplomacy" and "trans regional parallel diplomacy". Second, local governments at all levels in South Korea paid relatively low attention to the cities in the central and western regions far away from South Korea in the early stage. In the past 10 years, local governments at all levels in South Korea have gradually started to form sister cities with cities in the central and western regions of China. Third, the bilateral and multilateral cooperation system mechanism of local government cooperation between China and South Korea has gradually became mature. Fourth, various forms of local cooperation at different levels enrich the content of cooperation between China and South Korea and become an important platform for people to people and cultural exchanges between China and South Korea. If it is the geographical and ethnic factors that play an important role in the initial stage of local government exchanges and cooperation between China and South Korea, the policy system will become a new driving force for bilateral cooperation, and the policy promotion at the government level of China and South Korea will become an important consideration for the rational choice of local government transnational cooperation.

The countries of Northeast Asia have close ties and wide range of links in politics, economy, culture and geography. These countries have abroad humanistic foundation. It is of great significance to strengthen the regional cooperation in Northeast Asia under the vision of building the community of a shared future for mankind. This is conducive to safeguarding peace and stability in Northeast Asia, safe guarding the overall interests of Northeast Asia, promoting the common development of Northeast Asia, and realizing the “the Beltand Road” initiative. The idea of building the community of a shared future for mankind opensa new way of thinking for regional cooperation in Northeast Asia: focus in gon strengthening economic cooperation an destablishing cooperation mechanisms; strengthening mutual trust of political security and maintaining regional peace and stability; dealing with non-traditional security issues and curbing extremism; building a common concept and deepening regional identity. Therefore, building the community of a shared future for mankind and promoting regional cooperation in Northeast Asia can realize the overall realization of regional integration in Northeast Asia.

There has been heated debate between China and South Korea over the issue of THAAD deployment in ROK. From the standpoint of China, the deployment is a major issue which concerning the global strategic balance. It seems to China that the THAAD deployment will do nothing to solve the nuclear issue of north Korea,and it is beyond the South Korean defense needs. Moreover, it has seriously threatened China's security interest, undermined Sino-ROK relations and the trust between the big powers. The issue’s essence is the promotion of US deploying global anti missile system. For that ,China and Russia jointly defend the THAAD has become an inevitable trend. The Improvement of Sino-ROK relationship focus on the the national interest and prospects for denuclearization of the Korean peninsula. It means that the two sides have not changed their positions, and the THAAD problem has not really been turned over.

After DPRK's fourth nuclear test and the launch of the satellite, China and the United States stand on the opposite for the concrete measures of imposing sanctions on DPRK. Through repeated consultations, these two countries reached a limited “agreement” and the UN Security Council finally passed the resolution 2270 which expended sanctions against DPRK. The relations between China and DPRK raised concerns once again. As is known to all, China and DPRK established alliance relations in the form of treaty in the early 60s of last century. After the end of the cold war, the relationship between them began to fluctuate with ups and downs. And due to the continuous upgrading of the DPRK’s nuclear issue and the improvement of China-ROK relations, the China-DPRK alliance relations become “ambiguous”. In the future, under the circumstances of the game between superpowers is becoming increasingly fierce , the prospect of the unification of the Korean Peninsula is still not clear and DPRK’s nuclear program has not been stopped, China and DPRK should maintain the "alliance" relationship or turn to the normal state relations? The decisive factor depends on the nature of state interests and the essential requirement of geopolitical competition. China-DPRK ambiguous alliance is still likely to continue.