Key point: People’s war could start to look awfully like conventional marine combat if Beijing believes the military balance and the trendlines favor China.

Last year China’s defense minister, General Chang Wanquan , implored the nation to ready itself for a “people’s war at sea .” The purpose of such a campaign? To “safeguard sovereignty” after an adverse ruling from the International Tribunal for the Law of the Sea . The tribunal upheld the plain meaning of the UN Convention on the Law of the Sea (UNCLOS), ruling that Beijing’s claims to “ indisputable sovereignty ” spanning some 80-90 percent of the South China Sea are bunk.

A strong coastal state, in other words, cannot simply wrest away the high seas or waters allocated to weaker neighbors and make them its own.

Or, at any rate, it can’t do so lawfully. It could conceivably do so through conquest, enforced afterward by a constant military presence. Defenders of freedom of the sea, consequently, must heed General Chang’s entreaty. Southeast Asians and their external allies must take such statements seriously—devoting ample forethought to the prospect of marine combat in the South China Sea.

That’s the first point about a people’s war at sea. A clash of arms is possible. Statesmen and commanders in places like Manila, Hanoi, and Washington must not discount Chang’s words as mere bluster.

Indeed, it’s doubtful China could comply with the UNCLOS tribunal’s ruling at this stage, even if the Chinese Communist Party leadership wished to. Think about the image compliance would project at home. For two decades now, Beijing has invested lavishly in a great navy, and backed that navy up with shore-based firepower in the form of combat aircraft, anti-ship missile batteries, and short-range warships such as fast patrol craft and diesel submarines.

Party leaders have regaled the populace with how they will use seagoing forces to right historical wrongs and win the nation nautical renown. They must now follow through.

It was foolish to tie China’s national dignity and sovereignty to patently absurd claims to islands and seas . But party leaders did so. And they did so repeatedly, publicly, and in the most unyielding terms imaginable. By their words they stoked nationalist sentiment while making themselves accountable to it. They set in motion a toxic cycle of rising popular expectations.

Breaking that cycle could verge on impossible. If Beijing relented from its maritime claims now, ordinary Chinese would—rightly—judge the leadership by the standard it set. Party leaders would stand condemned as weaklings who surrendered sacred territory, failed to avenge China’s century of humiliation despite China’s rise to great power, and let jurists and lesser neighbors backed by a certain superpower flout big, bad China’s will .

No leader relishes being seen as a weakling. It’s positively dangerous in China. As the greats of diplomacy teach , it’s tough for negotiators or political leaders to climb down from public commitments. Make a promise and you bind yourself to keep it. Fail to keep it and you discredit yourself—and court disaster in the bargain.

Like any sane leadership, Beijing prefers to get its way without fighting. Fighting, though, could be the least bad of the options party leaders have left themselves. Quite the predicament they’ve made for themselves.

Which leads to the second point. Judging from Chang’s words, small-stick diplomacy has run its course. Small-stick diplomacy was about deploying the China Coast Guard and fellow nonmilitary sea services to police waters Beijing claimed. It depicted China’s sovereignty in the South China Sea as a fact, and dared woefully outmatched rivals to reverse that fact.

Left unopposed, de facto Chinese sovereignty—a near-monopoly on the use of force within borders sketched on the map—would have become entrenched over time. Once it became the new normal, it might even have taken on an aura of legitimacy among seafaring states.

The UNCLOS tribunal struck China’s approach a grievous blow, collapsing the quasi-legal arguments underlying small-stick diplomacy. The tribunal’s decision makes it clear that Chinese maritime forces operating in, say, the Philippines’ exclusive economic zone are invaders or occupiers—not constables.

If Beijing can’t get its way through white-hulled coast-guard vessels, that leaves military force. Sovereign states deploy law-enforcement assets to police what is rightfully theirs. They deploy military forces to fight for things that are in dispute. Chang’s warlike talk implies that Beijing has abandoned the softly, softly approach and has tacitly admitted Southeast Asia constitutes a contested zone.

And the lingo he employs matters. People’s war is a Maoist phrase used to convey certain martial ideas. Mao Zedong’s Red Army waged people’s war to seize contested ground from Japanese invaders and Chinese Nationalists. It appears China now sees the South China Sea in similar terms—as an offshore battleground where rivals must be overcome by force.

But not by military force alone. Beijing won’t withdraw the coast guard, maritime enforcement services, or the fishing fleet—an unofficial militia—from embattled waters. They will stay on as part of a composite whole-of-government armada. But the People’s Liberation Army (PLA) Navy and Air Force will figure more prominently in the force mix.

In the days of small-stick diplomacy, the naval big stick posed an implicit threat from over the horizon. Philippine or Vietnamese mariners knew the China Coast Guard had backup if they defied it. In all likelihood Chinese commanders will flourish the big stick more promiscuously in the future—rendering the threat overt and visible rather than latent and unobtrusive.

Here’s the third point. A people’s-war-at-sea strategy will confront a motley coalition in which outsiders—America, maybe joined by Japan or Australia—supply the bulk of the heavy-hitting combat power. The Philippines is lopsidedly outgunned. Vietnam has pluck and a formidable military, but it can hardly stand up to the northern colossus without help.

The coalition’s curious makeup would furnish Beijing opportunities for coalition-breaking. China might reckon that any conflict in the South China Sea would be a “ war by contingent ” for the United States, a war in which Washington fixes the size of a force dispatched to support regional allies and instructs the commanders of that force to do the best they can with the resources they have.

Such strategies are excellent for troublemaking but seldom decisive in themselves. Lord Wellington, for instance, led a contingent ashore in Iberia in 1807. The expedition gave Napoleon a “Spanish ulcer,” a nagging commitment on a new front. Yet Wellington never kidded himself that he would win a continent-spanning war with a modest expeditionary force augmented by partisans and the Royal Navy.

Such an approach, in other words, would betray half heartedness on Washington’s part. After all, America would have embarked on an open-ended enterprise in a distant theater off the opponent’s shores without any real thought of victory. Half Heartedness kills in such ventures.

People’s war is about outlasting stronger foes under circumstances like these. If the weaker contender is a China, endowed with sizable reserves of hard power to tap, then that contender needs time. Its armed forces protract the campaign, both to gain time to muster more strength and to wear away at enemy combat strength.

In short, China could win even if it remains weaker than America in the aggregate. The PLA could narrow or reverse the balance of forces in the theater—overpowering the U.S. contingent at the place and time that truly matter. It could dishearten Washington. U.S. leaders might despair of sustaining the undertaking indefinitely. Or, China could outlast America—inflicting numerous tactical losses over a long time, and thus driving the price tag of preserving freedom of the seas higher than U.S. leaders are willing to pay. If America goes home, the venture collapses.

How, in operational and tactical terms, can PLA commanders bring this about? By hewing to their own warmaking traditions. China is politically and strategically predictable in the South China Sea yet operationally and tactically unpredictable. Politically and strategically predictable because party leaders painted themselves into a corner with domestic constituencies. Tactically unpredictable because that’s how Chinese forces have fought since the age of Mao.

Indeed, “active defense,” the concept whereby Mao codified his ideas about people’s war, remains the heart of Chinese military strategy. Just ask Beijing . To oversimplify, the conceit behind active defense is that a weaker China can lure a stronger pugilist into overextending and tiring himself before delivering a punishing counterpunch. Conjure up the great Muhammad Ali’s Rumble in the Jungle in your mind and you get the idea.

If the rope-a-dope approach works on a grand scale, Chinese forces can inflict tactical defeats that enfeeble the foe over time. Active defense, then, is all about harnessing tactical offense for strategically defensive campaigns.

To prosecute it, Chinese commanders seek out isolated enemy detachments they can assault on “exterior lines,” encircling and crushing them. The cumulative effect of repeated tactical setbacks wears down the strong—and could prompt their leadership to question whether the endeavor is still worth its hardships, perils, and costs. If not, cost/benefit logic will prod U.S. leaders toward the exit—and China will prevail even without an outright victory over allied forces.