Explainer | South China Sea: why are Philippines-Beijing tensions heating up and will US get involved?

Central to recent run-ins between the two sides are the Scarborough and Second Thomas shoals located inside Manila’s EEZ, but which Beijing claims as its own

China also deployed several coastguard vessels to patrol those areas, alarming the Philippines that has a defence pact with the US to protect it in the event of an attack

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Navy ships from the US, Japan and Australia take part in the first multilateral maritime cooperative activity at the disputed South China Sea on April 7. Photo: Armed Forces of the Philippines via AP

Published: 11:35am, 11 Apr 2024

An escalating diplomatic row and recent maritime run-ins between China and the Philippines, a US treaty ally, have made the highly strategic South China Sea a potential flashpoint between Washington and Beijing.

The issue will be a focus of trilateral meeting between US President Joe Biden, Philippines President Ferdinand Marcos Jnr and Japan Prime Minister Fumio Kishida in Washington on Thursday.

What are the flashpoints?

Central to recent stand-offs between the Philippines and China are two hotly contested features located inside Manila’s 200-nautical mile exclusive economic zone, but which Beijing claims as its own.

China uses the so-called nine-dash line that takes in about 90 per cent of the South China Sea to assert its claim to sovereignty over the Scarborough Shoal, a submerged reef coveted for its bountiful fish stocks, and the Second Thomas Shoal, home to a small contingent of Filipino sailors living aboard a rusty warship that Manila intentionally grounded in 1999 to further its territorial claims.

Why are things heating up?

The Permanent Court of Arbitration in The Hague ruled in 2016 that Beijing’s expansive claims via its nine-dash line had no basis under international law, handing the Philippines a landmark victory, but that has not stopped China, which rejects the ruling, from being more assertive.