NEARLY A QUARTER OF THE WORLD'S MARITIME TRADE GOES THROUGH THE SOUTH CHINA SEA, WHICH SITS BETWEEN CHINA AND A NUMBER OF ASIAN NATIONS, INCLUDING VIETNAM, THE PHILIPPINES, AND TAIWAN.

IN ADDITION, EXPERTS SAY IT HAS LARGE RESERVES OF OIL AND GAS.

IN RECENT YEARS, IT'S ALSO BEEN THE SITE OF CLASHES BETWEEN CHINESE COAST GUARD SHIPS AND PHILIPPINE VESSELS AS BEIJING TRIES TO EXERT ITS CLAIM TO VIRTUALLY THE ENTIRE SEA IN DEFIANCE OF INTERNATIONAL LAW.

A CONFRONTATION THIS PAST WEEK ON THE DISPUTED SOUTH CHINA SEA.

>> YOUR UNSAFE MANEUVERS ARE IN CLEAR VIOLATION OF YOUR OBLIGATION FOR SAFE CONDUCT.

JOHN: A CHINESE COAST GUARD SHIP SIDESWIPED A FILIPINO GOVERNMENT FISHING VESSEL AND FIRED ITS WATER CANNONS.

PHILIPPINE OFFICIALS SAID ITS VESSEL WAS ON A ROUTINE RESEARCH MISSION, COLLECTING SAND.

BUT THREE SMALL, UNINHABITED SANDBARS IN THE AREA ARE THE REASONS FOR HEIGHTENED TENSIONS.

BOTH CHINA AND THE PHILIPPINES CLAIM SOVEREIGNTY OVER THEM.

WHAT'S AT STAKE IS LESS ABOUT THE SANDBARS THEMSELVES THAN ABOUT THE BODY OF WATER SURROUNDING THEM, THE SOUTH CHINA SEA.

SINCE 1952, BEIJING HAS CLAIMED VIRTUALLY THE ENTIRE SEA, EVERYTHING INSIDE WHAT'S REFERRED TO AS THE 9-DASH LINE.

IN 2023, CHINA ADDED A TENTH DASH OFF TAIWAN.

THE PHILIPPINES, MALAYSIA, TAIWAN, AND VIETNAM ALL REJECT CHINA'S CLAIMS.

THAT WAS THE BACKDROP EARLIER THIS MONTH FOR THE ANNUAL JOINT U.S.-PHILIPPINES MILITARY EXERCISES KNOWN AS BALIKATAN, TAGALOG FOR SHOULDER-TO-SHOULDER.

9000 U.S.

TROOPS JOINED 5000 FILIPINO MILITARY PERSONNEL FOR LIVE FIRE DRILLS.

>> THIS TYPE OF TRAINING IS ABSOLUTELY INVALUABLE TO US.

TO BE ABLE TO GET OUT HERE TO OPERATE WITH OUR TREATY ALLY AND TO BE ABLE TO SET UP A DEFENCE LIKE THIS AND INTEGRATE ALL OF OUR SYSTEMS IS JUST REMARKABLE AND WE'RE REALLY GRATEFUL FOR THE OPPORTUNITY.

JOHN: SOME OF THE DRILLS COULD HAVE BEEN SENDING BEIJING A MESSAGE.

FOR INSTANCE, THE PHILIPPINE PROVINCE OF ZAMBALES, ALONG THE SOUTH CHINA SEA COAST, WAS THE SITE OF AN EXERCISE USING A U.S. MISSILE DEFENSE SYSTEM TO TARGET DRONES ACTING AS HOSTILE AIRCRAFT.

A 1951 MUTUAL DEFENSE TREATY BETWEEN THE UNITED STATES AND THE PHILIPPINES COMMITS EACH NATION TO DEFEND THE OTHER IF IT'S ATTACKED.

SECRETARY OF STATE MARCO RUBIO HAS SAID THE U.S.

COMMITMENT TO THE PHILIPPINES IS IRON CLAD.

ANDREW CHUBB IS A FELLOW AT ASIA SOCIETY AND A SENIOR LECTURER AT LANCASTER UNIVERSITY IN ENGLAND.

HELP US PUT WHAT WE JUST SAW IN CONTEXT.

THE CLASH WE SAW BETWEEN THE CHINESE COAST GUARD SHIP AND THE PHILIPPINE VESSEL, THAT DIDN'T JUST START THIS YEAR.

ANDREW: THAT'S RIGHT.

HESE PARTICULAR REEFS AND SANDBARS WERE REFERRED TO IN THE REPORT AS BEING THE SUBJECT OF SPORADIC INCIDENTS OVER THE LAST SIX OR SEVEN YEARS BUT THERE HAS BEEN A NOTICEABLE UPTICK IN THE ACTIVITIES IN THE CONFRONTATIONS THIS YEAR.

IN PARTICULAR WE SAW LAST MONTH CHINA REALLY GOING PUBLIC WITH A SOVEREIGNTY ASSERTION WITH THE UNFURLING OF A FLAG AND THE HIGH-PROFILE NEWS REPORTS LAYING CLAIM TO THIS PARTICULAR SANDBAR SANDY KEY.

SIGNIFICANCE OF THAT IS IT LIES A COUPLE MILES FROM THE PHILIPPINES MAIN MILITARY OUTPOST IN THE AREA WHICH HAS BEEN DOING SOME SIGNIFICANT UPGRADES AT OVER THE LAST FEW YEARS.

IT IS ALSO ONE OF CHINA'S MAJOR MOTIVE -- ARTIFICIALLY BUILT ISLAND OUTPOSTS.

IT IS THE SORT OF SCENE WHERE THERE IS A LIKELIHOOD OF FURTHER CONFRONTATIONS IF THIS TREND CONTINUES.

JOHN: WHY IS THE SOUTH CHINA SEA SO IMPORTANT TO CHINA?

ANDREW: FROM CHINA'S PERSPECTIVE THE DISPUTE IS MULTILAYERED.

IT STARTED AS A DISPUTE ABOUT VIOLENCE.

- - IT STARTED AS A DISPUTE ABOUT ISLANDS, PARTICULARLY THE SPRATLY ISLANDS AND THE PARACEL ISLANDS, BUT ALSO SCARBOROUGH SHOAL, WHICH HAS BEEN A PARTICULAR FLASHPOINT BETWEEN THE PHILIPPINES AND CHINA OVER THE LAST DECADE OR SO.

THROUGH THE 1970'S THROUGH THE 1990'S YOU HAVE THE INITIATION OF THE U.N. CONVENTION ON THE LAW OF THE SEA, AND IT'S COMING INTO EFFECT IN 1994, AND THAT SET SOME VERY CLEAR RULES ABOUT, THEY WERE ACTUALLY REFERRED TO BY THE FILIPINO CAPTAIN JUST NOW IN THE CLIP, SOME VERY CLEARLY RULES ABOUT WHAT YOU CAN AND CAN'T DO IN WHICH WATERS.

NUMBERS PUT ON THE KIND OF DISTANCE THAT YOU CAN CLAIM OFF OF A PARTICULAR TYPE OF FEATURE, ET CETERA, ET CETERA.

AND CHINA WAS THERE AT THE INCEPTION FOR THAT PARTICULAR CONVENTION, WHICH THE U.S. HAS NEVER SIGNED, BUT WHICH NOW CHINA IS KIND OF FLAGRANTLY STRUGGLING AGAINST THOSE RULES.

THAT WAS REALLY DEMONSTRATED, CAME TO A HEAD IN 2016 ARBITRATION THAT THE PHILIPPINES BROUGHT.

AND THEN LAYERED ON TOP OF ALL OF THAT, YOU'VE GOT NOW THE U.S./CHINA GEOSTRATEGIC PLAYING OUT ALSO IN THE SOUTH CHINA SEA AND OTHER MARITIME LITTORAL AREAS IN EAST ASIA, SUCH AS THE EAST CHINA SEA.

JOHN: A LOT OF AMERICANS, WHEN THEY THINK ABOUT THIS REGION, THEY THINK ABOUT CHINA'S DESIGNS ON TAIWAN.

BUT COULD THE SOUTH CHINA SEA BE JUST AS VOLATILE OR EVEN MORE VOLATILE THAN THAT?

ANDREW: THE SHORT ANSWER IS YES, IT COULD.

THE BIG DIFFERENCE WITH THE SOUTH CHINA SEA AND TAIWAN IS THE NUMBER OF PLAYERS IN THE AREA.

SO YOU'VE GOT THE PHILIPPINES, VIETNAM, YOU'VE ALSO GOT MALAYSIA, BRUNEI MAKES A CLAIM THERE, TAIWAN OCCUPIES THE BIGGEST NATURALLY FORMED ISLAND.

SO YOU'VE GOT MANY DIFFERENT PLAYERS OPERATING IN THE AREA AND THAT'S BEFORE YOU BRING IN THE SORT OF EXTRA REGIONAL POWERS SUCH AS THE UNITED STATES.

ALSO THE U.K. HAS BEEN THERE RECENTLY, AUSTRALIA, JAPAN, SOUTH KOREA HAS DONE SOME PATROLS THERE AND OTHER EUROPEAN NAVIES AS WELL HAVE BEEN TALKING ABOUT, IF NOT ACTUALLY STEPPING UP TO FILL SOME OF THE THE STRATEGIC GAP.

JOHN: ANDREW CHUBB, THANK YOU VERY MUCH.

ANDREW: MY PLEASURE.

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