The U.S. must respond to China's increasing aggression in the South China Sea.

I note this concern in light of what occurred on Sunday, when a Chinese warship sailed within 45 yards of the front of the USS Decatur, forcing it to change course to avoid a collision. This action occurred in international waters and was a wanton breach of international law. Indeed, it was an outrageous breach: The Spratly Islands chain where the incident occurred is 700 miles from Chinese soil.

Geography ignored, China is behaving this way because it claims the South China Sea as its sovereign waters. Constructing artificial islands and positioning increasingly advanced weapons systems on those islands, China wants to give its regional neighbors and international exporters a simple choice: submit in political fealty to Beijing or stop transiting international waters.

It is an obvious imperialist gambit and it must not stand.

That's where the Decatur comes in. To its credit, the Trump administration has escalated U.S. efforts to challenge China's imperialism by sending U.S. military ships and aircraft through the South China Sea. But facing the Decatur incident, it's clear the U.S. must now take added steps. To allow this escalation to go unchallenged will only embolden the Chinese to continue in form.

So what should be done?

First, the Trump administration must bring more allies into the fold. While the British and French navies recently transited the South China Sea, the waters have not seen a massed multinational show of force.

Such a show of force is necessary for two reasons. It would show Beijing that the international community recognizes China's imperial ambition and is determined to stand united against it, plus, it would deter China from further escalation. The U.S. should thus request that Australia, Britain, France, Germany, India, Japan, Malaysia, the Philippines, Singapore, and Vietnam all send at least one warship to participate in a joint patrol through the Spratly Islands chain. While Germany will probably refuse to participate, and Japan's inclusion will infuriate China, this unified display would challenge Beijing's ambitions. As important, it would put China in a catch-22 position. After all, if China used force against the vessels, it would isolate the international community and endanger its global economic hegemony strategy. And if China allowed the transit to proceed, it would dilute President Xi Jinping's global strategy.

The U.S. must also recognize the broader strategic implications of China's escalation here. Namely, that by endangering U.S. sailors, Xi has proved that he is willing to take big risks to displace the U.S. as the world's great influencing power. That challenge requires U.S. response in the form of President Trump doubling down on his friction-based policy towards Beijing. Trump should now announce new tariffs on Chinese telecommunications firms and impose export restrictions on U.S. firms that want to do business in China. The president should also work with Congress to grant the Pentagon more spending to develop new cyber- and electronic warfare capabilities, to build more attack submarines and underwater combat drones, and to speed up the delivery of standoff weapons such as anti-ship missiles.

Xi must know that the U.S. will fight and win if necessary. Xi's understanding of that reality is the surest means of preserving the peace.

Ultimately, the Decatur incident represents a marked development in Chinese escalation against American interests. Just as the man for whom the USS Decatur is named used a show of American resolve to bring the Barbary pirates to heel, Trump should educate China that he is resolved not to yield.