When comparing the bipolar systems in the twentieth and the twenty-first century we find that the risk of a limited war in Europe was low because of the extreme risk of it escalating to all-out war. The risk of a limited war in East Asia is higher because it is unlikely to escalate to all-out war. After Germany’s division and NATO’s and the Warsaw Pact’s respective establishment, Europe was split into two blocs. By the 1950s, a third world war was expected should either side invade the other. The stakes of inadvertent escalation were so high that they effectively stabilized the European continent. The Soviet Armed Forces, which only a few years prior to the Cold War had defeated Nazi Germany’s Wehrmacht in the greatest land battles in human history, posed an overwhelming threat to U.S. forces and allies in Europe. Its inability to match Soviet conventional army forces in Europe compelled the United States to introduce the principle of “massive retaliation,” which sought to deter limited war in the 1950s by threatening all-out war.

The United States is not similarly committed in East Asian waters today. The use of military force by the People’s Liberation Army (PLA) in East Asian waters is unlikely to pose an existential threat and risk a nuclear war. Washington can instead rely on its naval preponderance. It has not developed any strategy akin to “massive retaliation” to deter China and the PLA. Although China might use nuclear weapons if invaded and Beijing were occupied, it is much less likely, almost inconceivable, that Chinese leaders would risk a nuclear war with the United States because some of its naval ships were destroyed. In contrast to continental Europe, water barriers in East Asia makes China, the United States and U.S. maritime allies less concerned about survival and existential threats. Under these conditions, decisionmakers in the United States and China might be willing to risk war to solve maritime disputes in East Asia or launch a first strike against an opponent’s navy, calculating that a full-scale invasion or all-out war was less likely than if the superpowers were located on the same landmass.

Since U.S. deterrence relied strongly on nuclear weapons in the early years of the previous bipolar era, it made the threat of nuclear war more credible and strengthened stability in Europe. Because the U.S. military does not need to fight the PLA on the East Asian mainland to maintain a regional balance of power, the United States remains not only superior to China in nuclear capability but also at the conventional level. This makes a limited war more likely, since the U.S. threshold for using military force may not include the use of nuclear forces. Moreover, Chinese leaders, counting on their second-strike capability to prevent all-out nuclear war and on their belief in a clear firebreak between conventional and nuclear conflict, could interpret this situation such that they may risk a conventional first strike or a limited war at their own choosing, believing such adventurism would not spark a major or nuclear war. Soviet leaders in the 1950s, and even after Washington introduced its flexible response and countervailing strategy in the 1960s, could not rule out to the same extent that the United States would not use nuclear weapons in a limited war.

OTHER GEOGRAPHICAL conditions heighten the risk of limited war and will shape the relationship between the two poles in the twenty-first century. There are few periods in modern history in which a secure, dominating land power could focus on developing naval power and eventually sea power, as China has done today. It is unthinkable that any of China’s neighboring states would even consider invading China along its borders. In comparison to the Soviet Union, contemporary China has more secure borders, better access to the sea and is geographically more centrally placed in East Asia, with more favorable internal lines of communication to support its naval fleets and defend its territory. Geopolitics facilitates China’s maritime expansion, allows China to challenge the status quo in East Asia, fuels geopolitical friction between China and the United States and increases the risk of limited war. Without peer competitors on the Asian mainland, China can take greater risks in confronting the United States in East Asian waters. The result of the U.S. Navy and the PLA Navy increasingly interacting at sea is an intensification of rivalries and instability.

There was much more agreement about the status quo in Europe during the Cold War than there is in contemporary maritime Asia. The Soviet Union helped set the terms at the end of the Second World War, carved out its spheres of influence and shaped the regional balance of power in Europe. Today, China is rising within a system it did not shape. The separation of Taiwan from mainland China, among other outstanding territorial claims, adds weight to the longstanding view that contemporary China’s spheres of influence in the region do not reflect the country’s traditional regional dominance and suggests that Beijing will challenge the status quo. The Soviet Union did not claim territory in Western Europe or within the United States’ sphere of influence. China, on the other hand, has sovereign territory claims in maritime East Asia, which has long been the U.S. sphere of influence. This will increase instability in ways that were unseen in Europe and heighten the risk of crisis and limited war.

It is more difficult to draw red lines at sea. There is no East-West divide, no Berlin Wall and no Checkpoint Charlie in East Asian waters. There are no trip wires or commitments that are not inescapable. Instead, U.S. commitments around potential flashpoints in the South China Sea, the East China Sea and the Taiwan Strait are more uncertain. It is also harder to establish a security buffer at sea than on land. The sea cannot be conquered and occupied like land territories, as it is seamless and more difficult to control than land borders. Land intrusions can be repelled and territory retaken and restored. This is much more difficult at sea.

It is inherently more challenging to uphold the status quo at sea. For instance, during the stand-off with Soviet forces in Europe the United States did not face the ‘salami slicing’ tactic the Chinese government is using to challenge the status quo in East Asian waters today. Contemporary Chinese behavior is more difficult to deter since it does not threaten military invasion and includes the use of China’s maritime surveillance ships, coast guard and maritime militia.

The Soviet navy challenged the U.S. Navy at sea during the Cold War, but the two adversaries did not interact militarily within each other’s respective vital spheres of influence on the European continent in the bipolar era. U.S. tanks were not operating inside East Germany or East Berlin, and Soviet Armed Forces did not maneuver within the borders of NATO countries. In the new bipolar era, East Asian waters are the main contested area and theater of military operations. The fact that China and the United States will be peer competitors in the dynamic maritime domain increases the risk of limited war.

The contested area at sea in East Asia is a geographical space where a limited war between the superpowers can be largely confined to the maritime domain; where status quo and spheres of influence are challenged; where security buffers are lacking; where geopolitics provides the rising land power with opportunities to challenge the dominant sea power; but where polarity and geopolitics allow the United States to concentrate on balancing China’s regional ambitions. This makes a bipolar system concentrated in East Asia and U.S.-China relations more unstable than the previous bipolar system that was concentrated in Europe and U.S.-Soviet relations.

WITHIN A bipolar world, wrote Kenneth N. Waltz, “there are no peripheries.” Bipolar structural conditions suggest that any global event involves the interests of the two superpowers that are compelled to intervene across the world to safeguard their interests. A global zero-sum game follows from the condition of a two-power competition, argued Waltz. However, the sameness effect and the zero-sum thinking that are expected from a bipolar system are not evident in U.S.-China interaction in world affairs today. Similar geopolitical factors that heighten the risk of war in East Asia explain the different patterns of behavior by the United States and China as they compete for influence globally.

Geopolitical instability at the center in East Asia mainly accounts for diverging patterns of behavior. In contrast to the previous bipolar system, which experienced stability at the center in Europe and instability at the periphery or ‘third world,’ contemporary U.S.-China relations are set to be more unstable at the center in East Asia and more stable at the edges. Preoccupation with confrontation, instability and conflict in maritime East Asia is likely to prevent U.S.-China rivalry from becoming as intense in other regions of the world as U.S.-Soviet rivalry.

After Europe was stabilized into two blocs and spheres of influences during the early Cold War, the superpowers’ rivalry and conflict moved instead to other regions. The Korean Peninsula, Indochina, the Middle East, Africa, Latin America and Central Asia became theaters for the struggles and proxy wars of the two superpowers. In the new bipolar system, disputes in East Asia, from the Korean Peninsula to the East China Sea to Taiwan and the South China Sea remain unsettled and core concerns preventing superpower rivalry from spreading to other regions. Sino-American conflict in maritime East Asia will likely restrain global security confrontations and proxy wars in other regions that defined superpower relations during the Cold War.