After a flurry of diplomatic activity involving top European nations, President Xi Jinping is turning his attention to Southeast Asia as he left Beijing on Thursday for Vietnam and Singapore amid tensions over the South China Sea.

Chinese President Xi and Nguyen Phu Trong, Vietnam's Communist Party chief, address young people from both countries in Beijing, April 4, 2015. [Photo by Wu Zhiyi / China Daily]

President Xi, also general secretary of the Communist Party of China (CPC) Central Committee, will pay his first state visit to Vietnam since taking office in 2013 from Thursday to Friday at the invitation of General Secretary of the Communist Party of Vietnam Central Committee Nguyen Phu Trong and Vietnamese President Truong Tan Sang, signaling an improving relationship between Beijing and Hanoi.

Xi will leave Vietnam on Friday afternoon to make his first state visit to Singapore at the invitation of Singaporean President Tony Tan Keng Yam. The visit will mark the 25th anniversary of the establishment of diplomatic relations between the two nations.

He will meet with Tan and Singapore's Prime Minister Lee Hsien Loong and also attend signing ceremonies for cooperation agreements.

Liu Zhenmin, China's vice-foreign minister, said Xi may sign deals with Singaporean leaders covering finance, education, technology and urban management.

In recent years, China and Vietnam have seen more frequent exchanges between high-ranking leaders, closer economic and trade relations as well as people-to-people and cultural exchanges.

In September, Truong Tan Sang attended the ceremony in Beijing marking the 70th anniversary of the Chinese People's War of Resistance against Japanese Aggression (1937-45) and the World Anti-Fascist War.

Wei Ling, director and researcher at the Institute of Asian Studies at China Foreign Affairs University, said Xi's state visit to Vietnam will send a positive signal to the world as it watches the situation in the South China Sea.

"Xi's visit will not only serve as a stabilizer, but more importantly as a propeller." Wei said. "Despite existing differences, getting closer with Vietnam is a way of demonstrating confidence to the international community.

"China insists on shelving disputes when they can't be solved immediately, but that does not mean we cannot enhance our relations." Wei said.

Jia Duqiang, an expert on Southeast Asian studies at the Chinese Academy of Social Sciences, said Xi is visiting Vietnam and Singapore partially because of the significant roles and influence that they have within the Association of Southeast Asian Nations.

Xi will also meet with Taiwan leader Ma Ying-jeou on Saturday afternoon to discuss cross-Straits issues before he wraps up the visit.

It will be the first cross-Straits meeting between top leaders of both sides of the Taiwan Straits since the founding of New China in 1949.

Ni Yongjie, deputy director of the Shanghai Institute of Taiwan Studies, said he believes Singapore was chosen mainly because it has played a special role in relations in the past.

In April 1993, Wang Daohan, then-president of the mainland-based Association for Relations across the Taiwan Straits, and Koo Chenfu, chairman of the Straits Exchange Foundation in Taiwan, held a groundbreaking meeting in Singapore.

Ni said that Xi and Ma had many choices of places to meet, but Singapore was best. As a country whose main population has ancestral homes in China, Singapore has long played a positive role, he said.

"Singaporean leaders have maintained close relations with both sides over the years and earned their mutual trust," he said.