Whether it is intellectual property, territory, or human lives, China does not have the right to claim ownership over things that fundamentally do not belong to it. For reasons both moral and strategic, Biden must reject Beijing's latest outrage with immediate physical action.

 Escalating its global assault on democratic sovereignty and international law, China has now declared sole ownership over the Taiwan Strait.

The public assertion Monday follows reports that China has spent recent months lecturing U.S. officials that the strait is its sovereign territory — rather, that is, than largely being characterized by international waters.

An East China Sea waterway separating democratic Taiwan from Communist China, the strait extends 80 miles at its narrowest point. China claims that Taiwan is a breakaway province that must be re-subjugated under Beijing's rule. In contrast, the United States and many other democracies believe Taiwan is a sovereign democracy whose 24 million citizens are entitled to continued freedom.

Still, it's hard to overestimate the aggressive nature of China's latest claim. Declaring sovereignty over the strait, China is suggesting that the waterway is as much Chinese territory as Beijing or Shanghai are Chinese cities. In turn, China is providing a legal basis to justify the future use of military force to defend the strait from foreign intrusions. The U.S. and its allies, indeed the international community at large, cannot accept Beijing's invention of nonexistent sovereignty. Allowing that invention to succeed would make de facto China's seizure of Taiwan's democracy.

Moreover, it would send a distinct message of American weakness. Allowing Beijing to eviscerate international maritime law unilaterally would shatter the post-Second World War, U.S.-guaranteed understanding that international waters and airspace are shared spaces — areas open to all so as to benefit the peace, prosperity, and freedom of all.

It's obvious that General Secretary Xi Jinping is newly determined to test President Joe Biden. The Chinese leader wants his counterpart to see this declaration and pause in fear. He wants Biden to worry that any future U.S. military transits of the Taiwan Strait will risk the death of American sailors.

Biden must stare down this outrageous threat.

While a Navy spokesman has already affirmed that the U.S. will keep sailing through international waters, including the strait, those words don't mean anything unless Biden is willing to act in kind. As such, the president should immediately order a Navy transit through the strait in direct riposte to China's action. Biden should ask allies such as Australia, Britain, France, Japan, and India to join this show of resolve. If France and India reject that request, they will only expose their own weakness.

It would be a serious mistake to underestimate Xi's personal and political resolve on the Taiwan question. Nevertheless, any sign of U.S. weakness will only embolden the Chinese leader. A multilateral flotilla would be particularly valuable in this regard in that its presence would force Xi to choose between escalating against many nations at once rather than just the U.S. Were China to fire on or harass the flotilla, it would put immense pressure on the European Union to impose its own sanctions on Beijing and further isolate China's global interests. This is a priority concern among Chinese leaders following the relatively united and strong Western isolation of Russia that has followed President Vladimir Putin's war in Ukraine.

We must not allow ourselves the comfortable delusion that this is only about Taiwan. China's clawing ambitions reach far further.

Without notifying Tokyo, for example, China just sent an undersea survey vessel into Japan's exclusive economic zone. The U.S. is also involved in a standoff with China over the freedom of the South China Sea. Those international waters account for approximately $5 trillion in annual trade flows. So, if China is able to consolidate its claims of ownership over the near entirety of the South China Sea (only by seeing a map can you understand how ridiculous these claims truly are), it will be able to extract the political fealty of sovereign nations in return for its allowing their import-export markets.

Whether it is intellectual property, territory, or human lives, China does not have the right to claim ownership over things that fundamentally do not belong to it. For reasons both moral and strategic, Biden must reject Beijing's latest outrage with immediate physical action.