China’s Hidden Navy

Chinese "fishing boats" around contested islands are part of an extensive maritime militia.

BY GREGORY POLING

The Chinese People's Liberation Army (PLA) Navy aircraft carrier Liaoning participates in a naval parade near Qingdao in eastern China's Shandong province, on April 23, 2019. 

The Spratly Islands, occupied by five different claimants, are the most hotly contested part of the South China Sea. 

Thanks to the harbors and supporting infrastructure Beijing constructed on its outposts there over the last five years, most vessels operating around the Spratlys are Chinese. 

And most of those are at least part-time members of China’s official maritime militia, an organization whose role Beijing frequently downplays but that is playing an increasingly visible role in its assertion of maritime claims.

Writers affiliated with Chinese institutions and state media seek to present an alternate version of reality by artfully cropping satellite imagery, cherry-picking data, or simply ignoring the facts and attacking the motives of those presenting evidence of militia activities.
This is unsurprising—the purpose of employing a maritime militia is to keep aggression below the level of military force and complicate the responses of other parties, in this case chiefly the other claimants (Vietnam, the Philippines, Malaysia, and Taiwan) as well as the United States, by hiding behind a civilian facade. 

Without deniability, the militia loses much of its value. 

That gives China a strong incentive to dissemble and deny evidence of its actions. 

But that evidence speaks for itself.
The People’s Armed Forces Maritime Militia is not a secret. 

Article 36 of the China Military Service Law of 1984, revised in 1998, calls for the militia “to undertake the duties related to preparations against war, defend the frontiers and maintain public order; and be always ready to join the armed forces to take part in war, resist aggression and defend the motherland.” 

China’s 2013 defense white paper enhanced the maritime militia’s role in asserting sovereignty and backing up military operations. 

This is the naval analogue to China’s larger and better-known land-based militia forces, which operate in all Chinese theater commands, supporting and under the command of the People’s Liberation Army (PLA).
In 2013, Chinese dictator Xi Jinping visited the maritime militia in Tanmen township on Hainan, China’s southernmost province, and labeled it a model for others to follow. 

Andrew Erickson, Conor Kennedy, and Ryan Martinson at the China Maritime Studies Institute at the U.S. Naval War College have spent years documenting the activities of the maritime militia, including extensive acknowledgment by Chinese authorities and many instances in which militia members have publicly discussed their activities.
A review of available remote sensing data by the Center for Strategic and International Studies and Vulcan Inc.’s Skylight Maritime Initiative, including infrared imaging, synthetic aperture radar, and high-resolution satellite imagery, shows that the largest number of vessels operating in the Spratly Islands belongs to the Chinese fishing fleet, which frequently numbers between 200 and 300 boats at Subi and Mischief Reefs alone. 

This is not by itself peculiar: China maintains the world’s largest fishing fleet, and its distant water vessels operate around the globe due to overfishing and pollution of Chinese coastal waters. 

But the vessels operating in the Spratlys are not part of that distant water fleet—those boats are larger and head farther afield in the hunt for high-value migratory species. 

And at 800 nautical miles (about 920 miles) from the mainland, the Spratlys are too far for small and medium-sized Chinese fishing vessels to operate productively without being heavily subsidized.
But even China’s two-decade-old policy of subsidizing fishing as an assertion of sovereignty can’t explain the behavior of most Chinese vessels in the Spratlys in recent years.

Chinese fishing boats in the islands average more than 500 tons, well over the size legally required for boats undertaking international voyages to use Automatic Identification System (AIS) transceivers, which broadcast identifying information, headings, and other data about oceangoing vessels. 

But fewer than 5 percent of them actually broadcast AIS signals at any given time. 

This suggests a fleet intent on hiding its numbers and actions.
These large, modern vessels represent a stunning level of sunk capital costs but do not engage in much commercial activity. 

Frequent satellite imagery shows that the vessels spend nearly all of their time anchored, often in large clusters. 

This is true whether they are inside the lagoons at Subi and Mischief Reefs or loitering elsewhere in the Spratlys. 

Operating in such close quarters is highly unusual and certainly not the way commercial fishing vessels usually operate.
Light falling net vessels, which account for the largest number of Chinese fishing boats in satellite imagery of the Spratlys, very rarely have their fishing gear deployed. 

China’s trawlers, meanwhile, almost never actually trawl; instead, satellite imagery and the AIS signals of those few trawlers regularly broadcasting both show that they spend most of their time at anchor. 

These unusual, and highly unprofitable, behaviors suggest that most of these supposed fishing boats are not making a living from fish.
When Chinese fishing vessels are not at Subi or Mischief Reefs, they are most often seen in satellite imagery anchored near Philippine- and Vietnamese-held outposts in the Spratlys. 

This is corroborated by the small number of AIS signals detected from Chinese ships. 

The most spectacular example of this behavior was the swarm of vessels from Subi Reef that dropped anchor between 2 and 5 nautical miles from Philippines-held Thitu Island as soon as Manila began modest upgrade work on that feature in December 2018. 

The number of vessels seen in satellite imagery peaked at 95 on Dec. 20, 2018, before dropping to 42 by Jan. 26. 

That presence continued into early June, when reports suggested that China had begun to pull back the vessels. 

The exact number of ships fluctuated from day to day, but almost none broadcast AIS or deployed fishing gear, and they operated in much closer quarters than any commercial fishing vessels would.
The Armed Forces of the Philippines confirmed that it had monitored 275 individual Chinese vessels swarming near Thitu between January and March, and Manila filed protests with Beijing over their presence. 

Meanwhile satellite imagery from March to April showed another cluster of Chinese vessels displaying the same puzzling behavior around two other Philippine-held features: Loaita Cay and Loaita Island. 

In that case, some dropped anchor just half a nautical mile from the isolated Philippine facility on Loaita Cay.
The only explanation that can make sense of all of these behaviors is that most of these vessels engage in the work of China’s maritime militia. 

The job of that militia force has been well documented by sources as diverse as the U.S. Naval War College, reports from the Philippine military, and China’s own official documents outlining the militia’s role. 

On a day-to-day basis it serves as a logistics and surveillance arm of the PLA, ferrying supplies to Chinese outposts, monitoring and reporting on the activities of other claimants, and engaging in joint training exercises with the military and law enforcement. 

But they also move into more direct harassment of other nations’ vessels when called up—maneuvering dangerously close to foreign naval, law enforcement, and civilian vessels, sometimes shouldering and ramming them, and in general making it unsafe for other parties to operate in areas contested by Beijing, all while the PLA and China Coast Guard are kept in reserve as an implicit threat with a level of deniability.
Some analysts have offered alternative explanations for the curious, unproductive behavior of these ships. 

But none of the theories stand up well to scrutiny.
One suggestion is that these vessels never have gear in the water because they are actually reef fishers engaged in harvesting high-value species such as sea cucumbers and giant clams. 

Relatedly, theorists posit that they don’t broadcast AIS because they are too small, or too old, or because they know that harvesting endangered species is illegal under Chinese law and they want to hide their activities. 

Some have even argued that the flood of vessels around Thitu was due to a surge in demand for seafood ahead of China’s Spring Festival.
But these explanations make little sense. 

The sizes and types of vessels are easily determined from satellite imagery. 

These fleets consist of large (over 160-foot) modern trawlers and falling net vessels, not the smaller (80- to 115-foot) motherships that accompany Chinese reef fishers around the Spratlys and other disputed features such as the Paracels and Scarborough Shoal, and certainly not the reef fishing boats themselves. 

And while reef fishing vessels average just 15 feet, they can be seen in satellite imagery; it would be immediately obvious if hundreds were operating around Thitu Island. 

There is plenty of sea cucumber harvesting in the Paracels—at Antelope Reef, for instance—and giant clam poaching has been well documented across the South China Sea. 

This is not that.
Another theory is that these vessels don’t appear to be fishing because they are involved in transshipment, serving in a support role by purchasing catch from and providing supplies to other fishing boats in the area. 

That might fit if it was just some small percentage of the Chinese fleet involved. 

But the opposite is true: Most Chinese ships observed in the Spratlys don’t appear to be commercially fishing. 

They can’t all be support vessels; what would they be supporting?
A third hypothesis is that some of these vessels are simply passing through the Spratlys to fraudulently collect the fuel subsidies China offers for ships that operate in the contested waters. After securing their subsidy, the theory goes, these boats likely head for more productive fishing grounds beyond the region. 

This could be true for some small number of ships; it would be impossible to prove either way. 

But this cannot explain the long-term presence of hundreds of vessels anchored around Thitu and other features. 

And while only a small percentage of Chinese ships broadcast AIS in the Spratlys, those that do tend to spend months at a time there, mostly anchored.
The evidence that China is using hundreds of fishing vessels under the aegis of its publicly acknowledged maritime militia to assert claims and harass its neighbors in the Spratlys is considerable. 

By contrast, the alternative theories are severely lacking. 

No other convincing explanation has been offered for why so many fishing vessels are engaged for months at a time in activities that make little or no commercial sense, or why they are so intent on hiding their actions.
The maritime militia is the vanguard of China’s assertion of claims to the waters of the South China Sea. 

It is the largest fleet operating in the area and is the most frequent aggressor toward both China’s neighbors and outside parties like the United States when asserting international rights in waters claimed by Beijing. 

It operates as a nonuniformed, unprofessional force without proper training and outside of the frameworks of international maritime law, the military rules of engagement, or the multilateral mechanisms set up to prevent unsafe incidents at sea. 

The next violent incident to take place in the South China Sea is far more likely to involve the Chinese militia than the PLA or China Coast Guard, and it will lack the mechanisms for communication and de-escalation that exist between those professional services and their counterparts in other nations.
The only way to avoid an eventual crisis triggered by these paramilitary vessels is to convince Beijing to take them off the board. 

And the first step is to pull back the curtain of deniability, acknowledge that the evidence for their numbers and activities is overwhelming, and insist that the Chinese government be held accountable for their bad behavior.

US warns China on aggressive acts by fishing boats and coast guard

Navy chief says Washington will use military rules of engagement to curb provocative behaviour 

By Demetri Sevastopulo

Chinese coast guard vessels in disputed waters in the South China Sea 

The US has warned China that it will respond to provocative acts by its coast guard and "fishing" boats in the same way it reacts to the Chinese navy in an effort to curb Beijing’s aggressive behaviour in the South China Sea. 

Admiral John Richardson, head of the US navy, said he told his Chinese counterpart, vice-admiral Shen Jinlong, in January that Washington would not treat the coast guard or maritime militia — fishing boats that work with the military — differently from the Chinese navy, because they were being used to advance Beijing’s military ambitions. 

 “I made it very clear that the US navy will not be coerced and will continue to conduct routine and lawful operations around the world, in order to protect the rights, freedoms and lawful uses of sea and airspace guaranteed to all,” Adm Richardson told the Financial Times. 

 On top of its militarisation of artificial islands in the South China Sea, Beijing has deployed paramilitary actors. 

In several incidents involving the US, Vietnam and the Philippines, Chinese fishing boats have rammed vessels, blocked access to lagoons, harassed ships and been involved in the seizing of reefs and shoals. 

 The maritime militia has been strengthened since 2015, when it created a headquarters in the China-administered Paracel Islands, a disputed area in the South China Sea that is also claimed by Vietnam and Taiwan. 

It has also received training alongside the Chinese navy and coast guard. 

In its last annual report on the Chinese military, the Pentagon said the maritime militia “plays a major role in coercive activities to achieve China’s political goals without fighting”. 

 China has increasingly used the maritime militia because fishing boats are less likely to prompt a military response from the US. 

But the latest warning significantly raises the stakes for China’s non-navy vessels engaging in aggressive acts. 

James Stavridis, a retired US admiral who also served as commander of Nato forces, said Adm Richardson was right to have delivered the tough message to the Chinese. 

 “It is a warning shot across the bow of China, in effect saying we will not tolerate ‘grey zone’ or ‘hybrid’ operations at sea,” said Mr Stavridis. 

“A combatant is a combatant is the message, and the CNO (Chief of Naval Operations) is in the right place to warn China early and often.” 

 Bonnie Glaser, a China expert at CSIS, a Washington-based think-tank, said: “By injecting greater uncertainty about how the US will respond to China’s grey-zone coercion, the US hopes to deter Chinese destabilising maritime behaviour, including its reliance on coast guard and maritime militia vessels to intimidate its smaller neighbours.” 

 William Choong of the International Institute for Strategic Studies, a Singapore-based think-tank, said the maritime militia gave the People’s Liberation Army Navy an “additional military arm” to help enforce Beijing’s stranglehold on the South China Sea. 

“It’s a clever strategy because the naval ships of the other claimants will think twice before they engage vessels that are technically not armed, not military ships, in a way they would other naval vessels,” he said. 

 The US warning also affects the Chinese coast guard. 

Dennis Wilder, a former head of China analysis at the CIA, said Xi Jinping put the coast guard under the control of the Central Military Commission in 2018. 

 “By having both the navy and the coast guard under the CMC, it improves in wartime the co-ordination and control of maritime forces,” he said. 

“As China’s coast guard is heavily armed, it is a logical assumption that it would be incorporated into military plans and operations.” 

 The US navy has been conducting Freedom of Navigation Operations, whereby it sends warships through disputed waters to prevent a claimant from denying others access in violation of international law. 

Analysts have long pushed for a more effective US response to counter China’s mix of military, paramilitary and economic coercive measures. 

 Andrew Erickson, a maritime militia expert at the US Naval War College, recently called for the US to “deal with China’s sea forces holistically” and state clearly that it expected China’s navy, coast guard and maritime militia to follow international rules. 

He added that the US had to “accept some friction and force Beijing to choose between de-escalating — the preferred US outcome — or to move up against a US red line that China would prefer to avoid”. 

The warning from Adm Richardson comes as the US takes a much tougher stance towards China over everything from commercial and traditional espionage to trade, technology transfer and intellectual property theft. 

Sina Delenda Est

How China Would Invade and Conquer Taiwan (And How to Stop It)

By Ian Easton

Taiwan's government and military (like the rest of Taiwanese society) are far tougher than they get credit for. 

But they can only do so much by themselves. 

The Pentagon has a critical role to play in assisting Taiwan maximize its war fighting capabilities. With America's help, Taiwan can make sure its defense investments factor into Beijing's calculations and, hopefully, prevent a future invasion from occurring in the first place.
Various sources from within the People's Republic of China have allegedly suggested that time is running out for Taiwan's democracy. 

In their narrative, China's iron-fisted leader, Xi Jinping, is "losing patience" and could order the invasion of Taiwan in the early 2020s. 

The world's most dangerous flashpoint might witness an overwhelming amphibious blitz, perhaps before July 2021 to mark the 100th anniversary of the founding of the Chinese Communist Party (CCP).
That's the narrative. 

The reality is that China will probably not attack Taiwan in such a radical and high-risk fashion. 

Xi and his top lieutenants are far more likely to draw-out and escalate the war of nerves across the Taiwan Strait. 

They will continue using disinformation and other techniques to drain Washington's confidence that Taiwan can be defended, while ramping up subversive activities to undermine the island nation's confidence and willpower.
Xi will bide his time and hope the Taiwanese government cracks under mounting pressure, allowing him to conquer his target cheaply. 

At the same time, his military generals will continue planning and preparing to deliver on their "sacred" mission. 

Coercion could easily fail, making invasion a tempting option―especially in a future scenario where the balance of power looks more favorable to Beijing than it does today.

Assessing the Threat:
The ever-tense political and security environment across the Taiwan Strait necessitates an accurate depiction of PLA capabilities, strengths, and shortfalls.
The PLA's strengths are more apparent than its weaknesses. 

China's military muscle is frequently highlighted and hyped up by the media, both in Beijing and abroad. 

Undoubtedly, China's ballistic missiles, cyber warfare capabilities, and counter-space weapons make it a force to be reckoned with. 

Perhaps even more dangerous are its espionage and covert actions abroad to shape foreign policymaking.
But there is always more to the story. 

Renowned Naval War College professor, Andrew Erickson, makes it clear in his recently published book, Chinese Naval Shipbuilding that while Beijing's fleets are growing at a remarkable clip, the PLA Navy is not ready to support the invasion of Taiwan. 

The Chinese navy still lacks the lift capacity and the air defense capability it needs. 

Nonetheless, the situation will almost certainly look very different tomorrow than it does today.
Dennis Blasko, author of The Chinese Army Today, observes that the CCP's ground forces, like the navy, are not yet ready for the ultimate fight. 

For invasion to be a realistic option, China would have to have far more helicopters, paratroopers, special operators, amphibious mechanized divisions, and marines. 

Moreover, the PLA would need to build a solid non-commissioned officer corps and provide better training to unit leaders up and down the entire chain of command. 

Much of this work has already begun and will start to bear fruit over the next decade.

Taiwan's Anti-Invasion Strategy:
So how do Taiwanese military experts plan to defend their country against attack, and how can the United States help?
Taiwan is at the tail end of a transit from a conscription force to an all-volunteer military. 

Building an elite force of professional warriors is a good thing. 

It gives Taiwan a comparative advantage. 

China has no national army and relies mostly on short-term draftees.
According to a recent RAND Corporation report, Taiwan could augment its all-volunteer military with elite reserve force units, further enhancing its ability to counter Chinese threats in the electromagnetic, air, and sea domains. 

Taiwan's armed forces could also benefit from new training opportunities. 

Bilateral training exercises and joint humanitarian missions with the U.S. military would give Taiwan a much-needed shot in the arm.
Modern wars are increasingly decided not by brute force, but by brainpower. 

This can only be harnessed with advanced training. 

One of Taiwan's primary defense goals is to prepare the island for the shock of a lightning war waged by the Peoples Liberation Army (PLA). 

Doing so requires highly-motivated personnel who are organized, trained, and equipped to meet an enemy invasion campaign with overwhelming resistance.
The asymmetry of size and economy across the Taiwan Strait requires defense planners on the island to harness every aspect of power, bringing a wide range of latent capabilities to bear when needed. Taiwan's all-out defense strategy calls for mobilizing the entire country, gearing-up every able-bodied man and woman in support of anti-invasion operations.
As Lauren Dickey of Kings College London points out, Taiwan's Ministry of National Defense (MND) is constantly honing its ability to repulse Chinese invasion. 

Every year, MND conducts intensive national and local-level military exercises, testing and sharpening plans to defend the island in the event of enemy landings.
It is estimated that Taiwan will have approximately four weeks advanced warning of a Chinese invasion. 

Given China's skill in the dark arts of strategic deception, this cannot be taken for granted. 

Yet the vast scale of the PLA's envisioned amphibious operations necessarily means its offensive intentions would be foreshadowed.
Warning signs would include troop movements, reserve mobilization, industrial stockpiling, military drills, media signaling, diplomatic messaging, and sabotage against Taiwan. 

The most obvious and worrisome sign would be the gathering of massive fleets of civilian and naval vessels at known amphibious staging areas in southeast China.
As all this was playing out, Taiwan's president, her cabinet advisors, and parliamentary leaders would debate their response options. 

They would weigh intelligence pouring in from radars, satellites, listening posts, and agents in China. Their most obvious option would be to increase readiness levels and mobilize the island to gun-down an enemy attack.
It would not take long to mine the maritime lines of approach across the Taiwan Strait, nor to fortify invasion beaches, ports, and airstrips. 

It would take only slightly longer to man all inland key points like bridges and power stations, and to evacuate non-essential personnel from potential battle zones. 

But accomplishing this would require a colossal workforce in the form of mobilized army reservists and contractors. 

For this reason, Taiwan maintains the ability to mobilize up to two and a half million men and nearly one million civil defense workers in just a few days time.
Tests of the emergency mobilization system are carried out on a yearly basis at sites across Taiwan, Penghu, and the outer islands (Kimen and Matsu). 

Their results are impressive. 

They indicate that citizen-soldiers will muster at marshalling posts in extraordinary numbers and at rapid speeds.
Taiwan’s all-out defense mobilization plan entails more than just bringing latent military capabilities into action. 

The Cabinet Office (Executive Yuan) and its subordinate ministries such as the Ministry of Transportation, Ministry of the Interior, and Ministry of Economic Affairs (among others) all play a role in the integration of civil defense units for homeland defense.

The Way Forward:
Taiwan's government and military (like the rest of Taiwanese society) are far tougher than they get credit for. 

But they can only do so much by themselves. 

The Pentagon has a critical role to play in assisting Taiwan maximize its war fighting capabilities. 

With America's help, Taiwan can make sure its defense investments factor into Beijing's calculations and, hopefully, prevent a future invasion from occurring in the first place.
The RAND report suggests the establishment of a joint working group, led on the U.S. side by an assistant secretary of defense. 

Indeed, Taiwanese forces would benefit from new types of professional military education and technical training in the United States. 

American mentors could support Taiwan’s continued transit to a potent all-volunteer force and help create a more strategically focused reserve force.
Taiwanese troops also need regular and dependable arms sales, something that unfortunately was denied them by the Bush and Obama administrations. 

For Taiwan, the positive operational and tactical effects of American weapons systems are indisputable. 

The Trump administration should offer Taiwan the same capabilities it is offering Japan and South Korea, including new stealth fighter jets, missile defense batteries, and destroyers.
In addition, American companies should be unchained by Washington, allowing them to compete for access to Taiwan's Indigenous Defense Submarine program. 

Even more important than firepower would be the huge morale boosting effects such material support would have on recruitment and retention on the island―and the powerful signal of purpose and resolve it would send to China.
Taiwan's military has developed a solid defense plan and is cultivating a force of professional warriors. 

But the grave invasion threat facing the island is growing over time. 

Keeping pace with China's offensive power will be extremely difficult unless big changes are made to the way America does business in Asia.
Going forward, the Trump White House would do well to develop a new strategy for advancing U.S.-Taiwan relations. 

Making sure Taiwan has the strong self-defense capabilities it needs will help keep the globe's greatest powder keg from ever igniting. 

Ignoring the China problem would only make it worse.

Why China Could Declare a South China Sea ADIZ Right About Now

By Harry J. Kazianis

The People’s Republic of China loves testing American Presidents. 

And, as the years have gone by, they’ve started doing it sooner and with more intensity.
Recent research seems to back up this assertion. 

As Andrew Erickson of the US Naval War College recently pointed out, Beijing undertook 44 “increasingly aggressive intercepts leading up to the EP-3 incident” back in 2001, only 77 days after George W. Bush entered the oval office. 

The crisis, according to Erickson, was “intended to test [Bush’s] intentions and persuade him to adopt a more conciliatory approach to China.”
Obama also had his own China test – this time a meager 44 days after his inauguration, in what is widely referred to as the USS Impeccable incident. 

According to Erickson, the move was designed as “part of a concerted Chinese effort to test [Obama’s] mettle and see if he could be pushed to reduce lawful US surveillance and reconnaissance operations in international waters and airspace.”
So what will Beijing do when it comes to Donald Trump? 

Let’s step back for a second and focus less on what China will do, but when it will do it— and that could be quite soon, as in now.
With Washington seriously distracted at home, the door is open for a number of actors (think not just China but Russia, Iran and/or North Korea) to make their move — and according to sources I have spoken with at the Pentagon, there is a real fear Beijing could make some sort of play fairly quickly.
I would argue that there could be no better time to test the Trump Administration from a Chinese perspective. 

In fact, there might not be a better time in the next several years to make a bold play in one of the strategically most important areas that Beijing considers its “core interest” and gain an important advantage over America. 

And these days, that likely means the South China Sea.
Consider where the United States is today, politically — a yuge, self-induced mess. 

Thanks to a number of what I would consider “unforced errors”, the new administration in Washington is constantly having to work through mini-crisis after mini-crisis. 

Whether it is the un-needed controversy over crowd sizes at the inauguration, near hourly “breaking news” over the latest Trump tweet and now a budding showdown over Trump’s executive action on refugees entering the country, foreign policy is not exactly front and center these days here in the nation’s capitol.
And from there things only get worse. 

There might not even be enough mid-level staffers, the backbone of many federal agencies, to respond to a crisis. 

When combined with the fact that many of the US State department’s most important positions are vacant, along with a rebooted National Security Council that just lost two of its most important members – none other than the heads of the Joint Chiefs and National Intelligence – there is what I could consider an obvious experience gap that is ripe for exploitation.
So, if China did decide to act swiftly, and specifically in the South China Sea, what would be its best play? 

My money is on an action that is bold, reinforces China’s claims of sovereignty and, most importantly, won’t be easy to retaliate against.
If I was Xi Jinping here is what I would do to test the new administration’s intentions and at the same time see Trump squirm: declare an Air Defense Identification Zone, or ADIZ, in the South China Sea.
Now, on the surface, such a move seems highly escalatory, and not in line with other Chinese moves intended to test Bush or Obama. 

However, the stakes in Asia are greater than ever before, and with President Trump’s rhetoric on the South China Sea and Taiwan much bolder than that of any other new US administration just taking office, China might decide quickly it needs to see where the rubber meets the road — and fast. 

And there is no better way to do that than a South China Sea ADIZ.
How would Beijing make such a move? 

Easy, just dust off the playbook it used in 2013 when China did the same thing in the East China Sea.
Beijing may not be able to actually police either sea with great credibility if Washington or Tokyo really decided to press the matter, and in fact, to this day – according to senior officials in the Pentagon I have spoken with – it does not enforce its claims “with much vigor”. 

Nevertheless, four years ago it was able to set an important marker in the East China Sea opposite Japan. 

In the South China Sea Xi might not be able to enforce the zone through the whole breadth of the massive nine-dash-line area, but he could create a credible military deterrent by permanently basing HQ-9 air-defense platforms and advanced fighter jets on as many of China’s “fake islands” as possible to make the zone as real as possible in a short amount of time.
So how would President Trump respond? 

Likely just as Obama did: send advanced bombers to fly into the zone right after it is declared. 

Trump could even order a naval response, conducting multiple freedom of navigation operations to make the point clear that Washington won’t ever fully accept China’s aggressive actions.
However, when it comes to such an ADIZ, it won’t be just China, America, or US allies who have the final say on its success or failure. 

Airlines that fly in the new the zone won’t risk their passengers lives with non-compliance and a possible shoot-down if a plane is misidentified, so they will of course send their flight plans to Beijing, making such a zone a reality.
But all of this should be no shock. 

A Chinese ADIZ in the South China Sea has been something that has been discussed and theorized for years now. 

And there might not be a better time to try and make it a reality.