The recent decline in US-China relations has many contributing factors that arise from the domestic politics of both countries.
The single most important trigger, however, is a key structural change: China becoming nearly as strong an economic and military power as the US.
The growth in China’s relative power has two important dimensions. The first, and most important, is economic. Deng Xiaoping’s outlook and reforms prepared the way for a long period of rapid economic expansion as China established itself as a global manufacturing center.
China’s economic growth rate has scarcely dipped below 5% since the late 1970s, while US growth was about 2.5% during the same period. This provided China with a bonanza of new wealth plus opportunities to acquire high technology.
The new wealth and infusion of technology made possible a huge upgrade in the second dimension of Chinese power, its military capabilities. Beijing recapitalized its military forces to stock them with modern warships, warplanes and missiles.
No more golden age
The latter part of the Cold War saw the beginning of the golden age of PRC-US relations.
China’s post-Cultural Revolution strategy of seeking prosperity through détente and engaging with the capitalist world economy was an important precondition – but the power differential between China and the United States set the parameters of their relations.

Because China was much weaker than the US, Chinese foreign policy reflected Deng’s famous advice that Beijing should avoid policies that might antagonize the Americans.
Perhaps the most severe test of this posture came with the 1999 bombing of the Chinese Embassy in Belgrade by US aircraft, which killed three Chinese nationals.
Despite considerable pressure for a stronger Chinese response, Communist Party General Secretary Jiang Zemin opted for a policy of expressing outrage over the incident, while leaving the bilateral relationship otherwise unchanged.
Similarly, when it was much stronger than China, the United States could afford to be magnanimous – tolerating many instances of Chinese cheating on agreements, poor international citizenship by Beijing and a lack of reciprocity in China’s favor without allowing these to seriously jeopardize the relationship.
The US government was willing to “be patient with China,” hoping if not expecting that by the time China became as big as the United States, American goodwill would have persuaded China to be a friend rather than an enemy.
Although it was improving, the Chinese military of the post-Cold War did not pose a major obstacle to US strategic freedom of maneuver in the region.

In recent years, however, China has reset the parameters by closing the power gap with the United States. It is this reset of the international system that has catalyzed changes in the domestic political thinking in both countries about the relationship.
China’s growth spurt evidently moved Xi to retire Deng’s foreign policy and shift to imposing China’s strategic agenda upon the region, even at the risk of alarming both the Americans and neighboring countries.
Previously ambivalent about US influence in the Asia-Pacific, China is now consistently critical of it, while also pursuing typical great-power territorial acquisition – Taiwan, South China Sea, East China Sea – under irredentist pretenses.
Washington realizes that a strong China can do significant harm to US interests. As the latest US Department of Defense report highlights, the US military must now expect to take heavy losses if it gets into a battle with Chinese forces on the western Pacific rim.
China’s economic centrality gives it immense political influence, as well, as states throughout the region see partnerships with China as essential to their prosperity.
Even US allies such as South Korea and Australia must think twice about siding with the United States against China in a political or strategic dispute.
Dramatic steps
This explains why the US government is now taking dramatic steps to reduce some aspects of US-China economic cooperation and other forms of bilateral engagement.
Even where Americans benefit in absolute terms, they are increasingly likely to cut off cooperation they perceive will benefit China more or will create long-term vulnerabilities for the United States.
A large trade deficit with China, dependence on China for vital supplies, unfair treatment of foreign investors in China and unfettered Chinese access to US technology, education and media are no longer tolerable.

From the US standpoint, Xi Jinping’s government certainly represents an illiberal retrogression in both its domestic and foreign policy. But Washington’s reaction to Xi would have been more relaxed were Xi’s unfavorable intentions not backed by strong capabilities.
Previously it was possible for China and the US to set latent mutual suspicions aside, but that has changed in an era of true peer competition over influence in the same region.
Nor will this era be brief, as the principal cause of deteriorating US-China relations is deeper than merely the preferences of current leaders Trump and Xi.
Denny Roy is a senior fellow at the East-West Center, Honolulu.