The strategic partnership between China and Russia has grown and changed since it was launched in 1996.
Its two major achievements since then have been the establishment of the multilateral Shanghai Co-operation Organization (SCO) and the expansion of bilateral trade.
But to further strengthen Sino-Russian relations, we should examine the basis of this partnership and identify obstacles in its path.
Concerns over US containment of Russia and China serve as the basis for Sino-Russian strategic co-operation. Since the Cold War, the United States has tried to isolate potential "threats" that challenge its status as the world's only super power.
It has placed China and Russia on its containment list and is unlikely to cultivate either as military allies in the next five years. In fact, the United States will continue to provide military support to Taiwan to constrain the development of China.
Until Russia reduces its stockpile of strategic nuclear weapons to a low level, the United States will also continue to view Russia as a potential danger to its interests and those of NATO.
Thus, China and Russia cannot ignore the importance of their strategic co-operative relations.
Arms trade is an important part of that partnership.
And the need for peace is the political basis of Sino-Russian relations. Both countries are now moving from a planned economy to a market economy. Both have set rapid economic development as their strategic goal, which requires a peaceful environment.
But the two countries face possible military threats from the Japan-US alliance in East Asia and NATO in Europe. They need to co-operate more to build safeguards against these alliances.
Yet some misgivings in Russia about China could erode trust between the two nations.
Russian media and politics have frequently discussed the "China threat." But Chinese people think their neighbour's concerns are groundless and insincere.
China will not invade other countries, and territory alone cannot make a nation a great power these days. China has reached an agreement on border issues with Russia and has no intention of becoming entangled in historic problems.
China and Russia have different geopolitical strategic emphases and the basis for strategic co-operation between the two is yet to be broadened.
Though both co-operate in central Asia, this region is not their most important geopolitical focus. Russia considers itself a European country, while China's focus is East Asia. Neither is interested in the other's regional issues.
But it would enhance trust between the two countries if the Russian Government did more to educate its citizens about China. Chinese people have comparatively favourable attitudes towards the development of Sino-Russian relations.
It is regrettable that the "China threat" still has its supporters in Russia.
It is impossible to achieve a consensus in public opinion under a democratic system, but it is possible for the government to guide mainstream opinions.
Public support for Sino-Russian strategic co-operation would certainly contribute to the long-term development of bilateral ties.
A detailed strategic co-operative principle would also help stabilize the relationship. The two countries have different security emphases, which means they do not share identical security interests but also have no major conflicts.
China and Russia could therefore consider supporting each other's regional security policies, avoiding official contacts with each other's separatist forces, and co-ordinating responses to international arms-control issues.
Developing a new multilateral security co-operation mechanism would also help. The two nations should co-operate more with countries in East Asia and Eurasia. France and Germany are willing to strengthen co-operation with China and Russia. If the four countries can co-ordinate on international strategic issues, it will create a more favourable environment for the economic construction of China and Russia.
Promoting non-governmental exchanges could provide another way to strengthen bilateral ties. Trade and business are the best channels for non-governmental exchanges. Besides increasing trade volume, China and Russia should make it easier to do business together. If new rules are not an option, the two can co-operate by exchanging business information first, which is a low-cost strategy.
The Sino-Russian strategic co-operative partnership can develop positively in the near future, but how much it grows depends on policy choices.
The author is a professor and director of the Institute of International Studies with Tsinghua University.