A new deal between Vietnam and China to resolve land and sea borders has been hailed as a major step forward.
Analysts say the deal will help avert fresh conflict between the two sides.
The two powers agreed in Beijing over the weekend to finish demarcating their land border this year, and to solve a maritime territorial dispute.
China and Vietnam have a tense relationship. Most recent disputes centre on the right to exploit oil and gas resources.
The weekend deal was signed in Beijing by the visiting Vietnamese Prime Minister Nguyen Tan Dung and Chinese Premier Wen Jiabao.
"The China-Vietnam joint declaration of October 2008 represents a very positive continuation of the process of confidence-building measures that has been under way for nearly a decade," said Dr Carlyle Thayer, visiting fellow at the Strategic and Defence Studies Centre at the Australian National University.
"It highlights areas for future co-operation and significantly sets up a hot line so the two sides can deal promptly with incidents, such as armed clashes, that arise from time to time," he told the BBC.
He said the agreement to finish the physical laying of boundary markers along the once-disputed 1,350 km (840 mile) land border was particularly important.
The agreement also offers a plan to demarcate the Gulf of Tonkin, establish a common fisheries area and conduct joint naval patrols from time to time.
The statement did not settle the issue of the Spratly Islands, a strategic string of rocky outcrops in the middle of the South China Sea claimed by several nations.
But China and Vietnam promised to "collaborate on oceanic research, environmental protection, meteorological and hydrological forecasts, oil exploration and information exchanges by the two armed forces," China's Xinhua news agency reported.
This builds on the resolution earlier this year of a potential conflict provoked by Vietnam's publishing of a Maritime Strategy for the exploitation of maritime resources.
China and Vietnam have an uneasy relationship.
China supported the Vietnamese Communists during the Vietnam War, but Vietnam is wary of its huge northern neighbour and, after a brief but bloody 1979 border war, lost 70 men in a brief naval battle in 1988.
The two neighbours normalised relations in 1991.