On December 10, a flotilla of 40 boats set off from the Philippine coastal town of El Nido in Palawan province to a group of islets and shoals in the South China Sea called the Spratly Islands, parts of which are claimed by several countries. 

More than 200 volunteers on this "Christmas convoy" wanted to deliver donated gifts and supplies to poor fishers living and working on boats in the Spratly archipelago, as well as to troops manning a purposely-grounded World War II-era vessel rusting away on a shoal that serves as a small Filipino territorial outpost.

The convoy was organized by a coalition called "Atin Ito" meaning "This is Ours" in Filipino. Besides bringing holiday cheer, organizers said they wanted to show the Philippines' presence in the Spratlys.

As the flotilla was making the crossing, they received word that the Chinese coast guard had confronted another nearby supply mission with water cannons, causing serious damage to one of the boats' engines.

And after being "shadowed" themselves by the Chinese coast guard, the organizers turned the flotilla back to El Nido.

2023 makes waves in the South China Sea

The incident is only the latest in an ongoing standoff that has escalated this year between the Philippines and China over disputed islets and shoals in the South China Sea, a resource-rich waterway claimed almost entirely by China.

For months, much larger and more modern Chinese coast guard vessels have been regularly confronting the Filipino coast guard, navy and fishing boats, sometimes ramming into them, and in one case earlier this year, using "military-grade lasers" to disorient crew.

The Chinese coast guard can patrol these waters off the west coast of the Philippines up to 24 hours a day from bases on artificial islands, built between 2014 and 2017 by dredging sand onto reefs and rocks.

One of these at Mischief Reef in the Spratlys is only 37 kilometers (23 miles) from the shipwreck outpost at Second Thomas Shoal, called Ayungin Shoal by the Philippines.

While it was building artificial islands, China also put together the largest coast guard in the world, which boasts decommissioned naval ships that rival the size of US destroyers.

China "now forward deploys dozens of coast guard and hundreds of militia boats in the Spratly Islands, 800 miles from the Chinese coast, around the clock," said Greg Poling, director of the Asia Maritime Transparency Initiative project at the Center for Strategic and International Studies (CSIS) in Washington.

To the north of the Spratlys is another disputed hot spot at Scarborough Shoal, a turquoise lagoon ringed by shallow reefs and rocks located about 120 nautical miles (222 kilometers) west of the Philippine island of Luzon. It is home to rich fishing grounds where Filipino fishermen play cat-and-mouse with Chinese coast guard boats.

China has bristled at the Philippines attempting to challenge Beijing's self-declared "indisputable sovereignty" over the shallow reef and rocks it calls "Huangyan Dao" and has occupied since 2012.

Scarborough Shoal is more than 460 nautical miles (851 kilometers) from the nearest Chinese shore at Hainan Island, and is well within the Philippines' Exclusive Economic Zone (EEZ).

In September, the Philippines infuriated China by removing a floating barrier the Chinese coast guard had set up in front of the lagoon entrance.

And the day before the Spratly Christmas convoy was being harassed by the Chinese coast guard, another Philippine supply mission to dozens of fishermen in the waters around Scarborough Shoal was attacked with Chinese water cannons, damaging vessels.

China's imagined islands

However, according to international law, there is no "legal" basis for Beijing's sweeping territorial claims under its so-called "nine-dash line," which is seen on maps protruding in a U-shaped tongue hundreds of miles south and cutting across the EEZs of the Philippines, Vietnam, Malaysia, Indonesia and Brunei.

In 2013, the Philippines challenged China's claims at the Permanent Court of Arbitration in The Hague. The international tribunal ruled in 2016 that China's claims to "historic rights and resources" within the nine-dash line had "no legal basis."

It also ruled that none of the "land features" China claims in the Spratlys could be considered capable of being the basis for legal territorial claims like an EEZ.

Beijing instantly rejected the ruling as "null and void," and has ignored it ever since.

South China Sea historian Bill Hayton has pointed out that the basis for the nine-dash line partly goes back to a 1936 map created by Chinese geographer Bai Meichu, who named and claimed islands that didn't even exist, some based on misinterpretations of permanently submerged sand rises published on existing Western maritime charts.

This includes "James Shoal" in the Spratlys, which to this day China says is the southernmost point of the country, even though it is over 21 meters underwater, is located 1,800 kilometers from the Chinese mainland, and is only 80 kilometers off the coast of Malaysia.

"This isn't about economics or resources, it's about nationalism. China's leadership has since the 1990s created its own historical fairy tale about 'historic rights' across these waters, and now it can't let it go even though it has become self-defeating," said CSIS expert Poling.

"China seeks to control all peacetime activity in the South China Sea because it has convinced itself that it has that right, and because [Chinese leader] Xi Jinping elevated the importance of this issue to his domestic political legitimacy," he added.

Rough waters ahead

Even if they are the result of somebody's imagination, the competing claims in the South China Sea are considered a real threat to security and stability in waterways that carry trillions of dollars in global trade.

The US Navy, among other Western navies, regularly leads "freedom of navigation" exercises in the South China Sea as a reminder of this.

After Ferdinand Marcos Jr. took over as Philippine president in June 2022, Manila rekindled its decadeslong defense partnership with the United States and signaled it would be less receptive to Chinese interests than was seen under the previous president, Rodrigo Duterte.

This included holding the largest-ever US-Philippine war games in April in the northern Philippines.

Chinese officials have repeatedly warned the US against intervening in the South China Sea, and consider Western interest in the disputed waters to be an "external force" in a strictly Asian affair.

Over the past year, Beijing has also shown it is willing to take larger risks, or at least appear to, in order to drum up domestic support from hardliners.

"Tensions around Second Thomas Shoal, and to a lesser degree Scarborough, have been increasing steadily for the last year as China has sought to block every Filipino resupply mission, and has been doing so with more dangerous tactics — lasers, water cannons, acoustic devices, and outright ramming," said Poling.

Philippine security officials fear China's next step could be taking over Second Thomas Shoal and building military installations there, as it did with nearby Mischief Reef, Reuters has reported.

In sending flotillas and supply missions in defiance of China's overwhelming material superiority, the Philippines is testing how far Beijing is willing to go, and whether the frequent attacks on its boats will be limited to water cannons in the future.

"The Philippine government under President Marcos is determined not to back down in the face of bullying, and the US has been clear that it will help defend Filipinos if China uses force," said Poling.

He added that the US backing, at least on paper, helps "give the Philippines more confidence that it can continue to run these Chinese blockades without the Chinese vessels opening fire."

"So far, that calculation has been correct, leaving China with no good options but to keep running this same dangerous play over and over every month, worsening its relationship with the Philippines and damaging its international reputation to no benefit."

Edited by: Srinivas Mazumdaru