China appears to be accelerating its campaign to control the South China Sea and the Senkaku Islands (pictured) in the East China Sea. Beijing does itself no favours with the highly ambiguous nature of its claims in the region. Its internationally condemned ‘nine-dash line’ sometimes appears to be delineating its claims to the island features within it. More ominously, Beijing sometimes insinuates the line as a maritime delineation, carving out sovereign control of the sea itself as well as the airspace above it.

China’s ongoing militarisation of many artificial features in disputed waters is well known. A less well known, but highly consequential implication of this militarisation is the vastly increased capacity it gives China to project power not only to control the reefs and rocks of the South China Sea, but, in the future, to assert control over the high seas and airspace above it. Beijing is vocal about its opposition to innocent passage and other military activities within its 200-nautical mile exclusive economic zones.

Beijing has tried hard to keep its dispute resolution efforts focused on bilateral negotiations between itself and the various claimants, effectively fracturing a united response by ASEAN. Pushback in the region is only now beginning. China’s sweeping claims also impact many countries that lie far beyond the shores of the South China Sea. The US, Japan, Australia, India and many others around the world have critical interests in using the sea directly for economic, scientific and military purposes. More urgently, maintaining an open and free system of movement through the high seas—and in the future, in outer space—is of critical importance.

The decisive rejection of China’s claims in the South China Sea by an arbitral tribunal under the UN Convention on the Law of the Sea in 2016 only accelerated Beijing’s continued bad-faith efforts to construct features, militarise them, and extend administrative control over others’ presence and activities to the furthest reaches of the nine-dash line. In fact, the ruling decisively rejects both China’s claims to many rocks and maritime features and the idea that these islands can generate territorial seas and exclusive economic zones.

This studied strategic ambiguity by China (on display on other fronts as well) should encourage the international community to confront an alternative and altogether darker explanation for Beijing’s behaviour—that it is building forces and positions in the region so that over the long term it can assert sovereign authority over the South China Sea.

This interpretation of China’s actions, though difficult to accept, should be considered as a possibility in military and strategic planning efforts around the world with an eye towards avoiding this worst-case outcome. It is important to remember that the scope and scale of China’s claims are unprecedented in international law and have no real analogue anywhere else on earth. An unwillingness to confront this scenario risks ceding Beijing permanent control over economic and military activities over a large and critical section of the world’s oceans—and beyond.

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The South China Sea is a third larger than the Mediterranean Sea and more than twice as large as the Gulf of Mexico. Acknowledging China’s sweeping claims to sovereignty over this massive space would increase the possibility of a future international environment in which ever larger portions of the global commons are cut off and controlled by individual nations.

Either the international community believes in maintaining a free and open global commons and protects international law or it doesn’t. If it doesn’t, then China’s potential annexation of this vast space will guarantee similar claims over the world’s oceans. To foreclose on this future will require an active and aggressive response by the widest grouping of states possible. Regardless of how individual claims over the various land features in the South China Sea are resolved, the entire globe has a stake in free and open access to the region.

For this reason, the US, along with all major allies and partners, should explicitly link China’s own access to the global commons with its behaviour in the South China Sea. Washington’s announcement of its rejection of Beijing’s maritime claims, underscored by the US Navy dual aircraft carrier strike group exercises in the region, is a good beginning. However, operations in the South China Sea play to China’s strengths. The US and the widest range of allies and partners in the international community should begin to articulate and apply escalating administrative and technical restrictions globally on Chinese shipping, air travel and transport in and through exclusive economic zones around the world by participating countries.

Restrictions on economic and military transit and scientific exploration should be pre-planned and scalable so that they are similar to Chinese moves in the South China Sea. These allied ‘grey zone’ competitive activities could be problematic for Beijing; they would drastically increase the cost and complication of accessing the Indo-Pacific region and beyond. For example, contiguous US, Japanese and Philippine zones restrict direct Chinese access to the Western Pacific. This possibility should be communicated to Beijing should it attempt to assert sovereign control in the South China Sea through force.

Securing the highest degree of freedom and access throughout the global commons should be the ultimate goal of this international effort. Focused and reciprocal restrictions on China throughout the exclusive economic zones of the world should be coupled with strong assurances that they remain open for participating nations. Moreover, these restrictions on China should be easily and quickly reversible. When Beijing comes to its senses on the use of the South China Sea, its access to the global maritime commons should be both restored and encouraged.

Although this strategic approach to countering Beijing’s most aggressive designs in the South China Sea appears to be rather drastic, like-minded nations around the world should be prepared to deliver a decisive shock to Beijing’s calculations about any gains it may achieve by limiting access to the South China Sea and rejecting the free use of the global commons more generally. Even hinting that a global response on this scale is possible should concentrate minds in Beijing on their strong and growing dependence on the global commons to reach their much vaunted ‘centenary goals’. Together, allied nations should encourage China to support an open and free global commons today in the South China Sea.