BEIJING, April 20 -- Since 2001, significant changes have taken place in the security relations between China and the United States, with a noticeable increase of positive factors and continuous strengthening of co-operation. The two countries have made important headway in building up strategic mutual trust.

　　There are two main reasons that have led to the major changes in Sino-US security relations: The United States has made significant adjustments to its assessment of security threats, and the basis for China-US co-operation on security has expanded considerably.

　　After the collapse of the Soviet Union and the end of the Cold War, the United States' suspicion about and guardedness against China was on the rise. However, the September 11 attacks jolted the United States into realizing that the main security threat was not from China, but from terrorism and the proliferation of weapons of mass destruction, especially from the combination of the two.

　　In the past four years, while busily fighting terrorism and preventing weapons proliferation, the United States has noticeably lessened its security pressure on China.

　　The September 11 incident also provided a new opportunity for China and the United States to co-operate on counter-terrorism and anti-proliferation. The two countries have seen their co-operation grow in recent years in the diplomatic, legal, financial and intelligence exchange aspects of counter-terrorism, while that in preventing proliferation has also advanced markedly.

　　At the same time, Sino-US co-operation in such areas as maintaining regional peace, alleviating regional confrontations and many other non-traditional security concerns has been growing in strength as well as scope. This includes fighting trans-national crime, fostering energy resources security, checking illegal immigration, preventing and treating continent-hopping epidemics and building defences against natural disasters.

　　Today, as globalization proceeds rapidly, threats posed by regional conflicts and non-traditional security challenges have become a common and growing concern in the world. To solve these problems, China and the United States have no other choice but to co-operate. Because the co-operation in low-political and non-traditional security is less susceptible to ideological and geo-political interference, its development is of great significance for nurturing mutual trust between the two countries.

　　As the basis of their security co-operation expands, China and the United States have also stepped up co-operation in maintaining the status quo across the Taiwan Straits in the last two years. This co-operation is of profound and far-reaching significance.

　　The Chinese mainland is sparing no efforts to maintain the Taiwan Straits status quo because it believes time is on its side, and, if the current basic mindset that both sides of the Taiwan Straits are parts of one China and the one-China principle enjoys international support, it is only a matter of time before the nation achieves the grand goal of peaceful reunification through unrelenting hard work.

　　Meanwhile, Washington hopes the status quo of the Taiwan Straits will stay undisturbed because it is too busy fighting terrorism to allow itself to be distracted by the emergence of tension in the Taiwan Straits, and it is even less willing to be dragged into a military duel with Beijing. Under the present conditions, there has emerged within the United States a suggestion, different from "strategic ambiguity" or "strategic clarity," for US-China "co-management" of the Taiwan Straits situation, indicating the United States is strengthening "management and control" over "Taiwan independence."

　　Another encouraging development is the full resumption of China-US military contacts following US Defence Secretary Rumsfeld's visit to China last year. The military contacts were suspended as a result of the South China Sea mid-air collision in 2001. Although this development still lags behind other aspects of Sino-US relations, there is hope that the ties between both armed forces will make greater headway through joint efforts, facilitated by a willingness from both sides to actively expand their relations.

　　Also worth mentioning is the gratifying effectiveness of the mechanism for bilateral dialogue that has enabled continuous improvement of Sino-US security relations. From frequent meetings of both heads of state to the initiation of strategic dialogue in 2005, and to a multitude of forms of bilateral and "first track" (official) and "second track" (dialogue conducted by scholars as well as officials in unofficial capacities through government-sanctioned channels) dialogue, the depth and scope of China-US dialogue has been growing non-stop, providing an important guarantee for the sustained development of bilateral security ties.

　　That said, however, there is clearly no denying that negative factors still exist in the way Sino-US security relations develop, with plenty of uncertainties looming over the horizon.

　　First up is the fact that there are still some differences between China and the United States over the latter's policies on counter-terrorism and proliferation, with those particularly prominent in China's criticism of US insistence on unilateralism, pre-emptive strikes and double standards. How these differences evolve will have a considerable bearing on the development of bilateral security relations.

　　The US policies in this respect have shown a positive sign of swinging back to multilateralism in the last two years, but it is hard to predict whether the trend will stay. The direction in which US policy on the Iran nuclear issue is headed is one such important weathervane.

　　Next is the serious difference between China and the United States over the issue of Taiwan. The United States has shown no sign of letting its "Taiwan Relations Act" go, and insists on selling weapons to, and upgrading military ties with, Taiwan, while some powerful forces within the country even dwell on the notion of keeping the Taiwan Straits in the state of "neither reunification nor independence" forever.

　　The shadow of military confrontation in the Taiwan Straits between China and the United States will be extremely hard to lift if this situation remains, forcing the armed forces of both countries to be on guard against each other. In the next two or three years, China-US security relations are likely to encounter new challenges as Taiwan secessionists will use the so-called "constitutional reform" to make more troubles.

　　Then there is the more profound question of China's development. As things are, the United States is still overly wary of China's future development and is concerned that China will challenge its leadership over security affairs in East Asia, or even challenge its military dominance in the world someday.

　　In its Quadrennial Defence Review published recently, the US Department of Defence has clearly put China at the head of countries "at the strategic crossroad." In the past two years, the United States has beefed up its military presence in the Asia-Pacific region, upgraded its military alliance with Japan, pushed harder for US-Japan-Australia military co-operation and US-Japan-ROK (Republic of Korea) military co-operation, and, while continuing to maintain a huge nuclear as well as conventional arsenal in the region, repeatedly demanded that China increase its military transparency. Though not entirely aimed at China, these measures were invariably taken with China in mind.

　　All in all, undeniable as the progress was that China and the United States achieved in their bilateral security relations over the past years, they still have a long way to go before they gain strategic mutual trust. It remains a long-term task for both countries to expand co-operation, reduce differences and clear away misunderstanding.