The Guardian-Confrontations in South China Sea surge raising fears a miscalculation could lead to conflict

Philippine Coast Guard personnel prepare rubber fenders after Chinese Coast Guard vessels blocked their way to a resupply mission at the Second Thomas Shoal in the South China Sea in March 2024.

Reports of aggressive and dangerous conduct by Chinese vessels in the fiercely contested South China Sea have surged over the past 17 months, as tensions mount in one of Asia’s biggest flashpoints.

Since February 2023, the Philippines has accused China of unsafe behaviour on at least 12 occasions, often within the water of its exclusive economic zone (EEZ), according to Philippine government data compiled by the thinktank the International Institute for Strategic Studies (IISS), which tracks incidents as part of its regional Asia-Pacific Regional Security Assessment.

It comes as the Philippines marked the eight-year anniversary of a Hague tribunal ruling that overwhelmingly backed the Philippines, and rejected China’s sweeping claims over the South China Sea.

The Philippine ambassador to the United States, Jose Manuel Romualdez, told the Guardian tensions and “aggressive movements” needed to be reduced to “avoid a situation where something really major, conflict, can happen”.

On Friday, the Philippines national security adviser, Eduardo Ano, said the country would not back down. “We will continue to stand our ground and push back against coercion, interference, malign influence and other tactics that seek to jeopardise our security and stability,” Ano said.

Reported incidents include accusations China has rammed Philippine vessels, used water cannon on them, damaging their ships, deployed a military-grade laser against its coast guard, and, most recently, used knives to puncture its rubber boats.

Previous years might see fewer or more minor incidents recorded, although Meia Nouwens, senior fellow for Chinese security and defence policy and head of the China Programme at IISS, said collating data on confrontations was difficult as it was possible that some incidents were not publicly disclosed by past governments.

The frequency of encounters between Chinese and Philippine coast guard or navy personnel that involve contact is also higher than in recent years, when reports of rammings or water cannon deployment were rare, and analysts say the current tensions have risen to levels not seen over the past 10 years.

“The recent tensions have been much more physical, there’s been a lot more contact between Philippine and Chinese ships,” said Harrison Prétat, deputy director and fellow with the Asia Maritime Transparency Initiative, who added that while there have previously been spikes in tensions between Vietnam and China, the Philippines is a US treaty ally. “One factor that makes this situation perhaps even more concerning is that there is this treaty obligation of the United States to the Philippines.”

The US has pledged to defend Manila in the event of an armed attack, and as reported incidents become more frequent and more intense, there are growing concerns that a miscalculation could pull the US into direct confrontation with Beijing.

The dispute over the South China Sea is long-running and volatile, and China has for years been accused of aggressive acts against neighbouring country’s vessels.

China has repeatedly denied acting unprofessionally, saying its coast guard operates legally and with restraint. However, video and images released by the Philippines coast guard has frequently appeared to support its allegations, as has independent media reporting.

The South China Sea is one of the world’s most important trade routes, and a strategically important waterway, but it is at the centre of a fierce dispute. Beijing claims the majority of the sea through a controversial demarcation known as the nine-dash line – despite a ruling by a Hague tribunal finding such claims to be without legal basis. Its claims not only clash with those of the Philippines, but also Vietnam, Malaysia, Brunei and Taiwan.

Dangerous confrontations have mostly occurred when Philippine vessels attempt to conduct resupply missions to a small contingent of troops based at Second Thomas Shoal, a submerged reef in the Spratly Islands that sits within the Philippines’ EEZ. The soldiers are based at a rusting and dilapidated ship, BRP Sierra Madre, which was deliberately grounded at the shoal in 1999 by the Philippines to underline its claim to the shoal, and which continues to serve as an unlikely military outpost.

China has demanded the ship’s removal and argues that Manila’s resupply mission are trying to deliver construction materials to reinforce the ship.

Analysts say Beijing has essentially imposed a blockade on the Sierra Madre, which is severely degraded after more than two decades at sea, and warn China could take the shoal in the event the ship crumbles.

Romualdez said the Philippines “cannot and will not” abandon its presence at the shoal, but he added that its coast guard was committed to acting with restraint.

Deliveries had been “misconstrued as construction material”, he said, adding the purpose was not offensive in nature but intended to make the Sierra Madre safe for those who are based there. “It’s the typhoon season right now, a big typhoon can very well happen, and then our soldiers who are there can obviously be in harm’s way,” he said.

Facing China’s ‘monster’ ship

In addition to unsafe conduct, the Philippines has also accused China of wider intimidation tactics, including the anchoring of a 12,000-ton Chinese coast guard, known as “the monster”, due to its size, inside Manila’s EEZ, just 730 metres (800 yards) away from a Philippine coast guard ship at Sabina shoal. A state’s EEZ extends 370km (200 nautical miles) from the coast, and it has special rights to exploit resources and construct in this area.

In June, China also introduced a new regulation that empowers its coast guard to detain foreigners accused of trespassing, and detain them for up to 60 days without trial, a move that has created greater anxiety among Filipino fishing communities.

The Philippines has insisted it will not relent in defending its waters, however it faces a difficult decision about how to continue resupplying the Sierra Madre.

“It’s getting more and more clear that this is a blockade,” said Ray Powell, director of SeaLight, a maritime transparency project at Stanford University. “China’s got almost a semi-permanent [presence], they’ve their own small boats in and around the Sierra Madre, with a tight cordon.”

Philippine president Ferdinand Marcos said last month that if any Filipino serviceman or citizen were killed by a wilful act in the South China Sea, this would be “very, very close to what we define as an act of war, and therefore, we would respond accordingly”.