Explained: South China Sea dispute and the wider geopolitical power-play

US Secretary of State Antony Blinken has vowed “ironclad support” to the Philippines as he began a high-profile visit to the South Asian archipelagic country, where he is expected to make security commitments amid soaring tensions between Manila and Beijing in the South China Sea.

The US has described the Philippines as a US "key strategic hub", with China seeking to push back against Washington’s influence in the Indo-Pacific region.

Blinken's visit occurs amid the Philippines' regional pivot away from Beijing and closer alignment to Washington. Former President Rodrigo Duterte enjoyed closer ties with China, while President Ferdinand Marcos Jr. has shifted towards Washington.

In recent months, heightened tensions between the Philippine and Chinese Coast Guards have resulted in clashes between vessels of both nations.

Beijing claims that live-fire exercises by the Chinese People's Liberation Army (PLA) are important to safeguard China's territorial and maritime rights amid what it calls the Philippines' "repeated provocation" in the South China Sea "under the instigation of the US".

The US has pushed back against China, calling for it to "desist from its dangerous and destabilising conduct".

In 2014, Manila and Washington inked a deal for US aid in developing Filipino military bases and deploying US troops on a rotational basis. Almost a decade later, the US gained access to four more bases.

The US base's proximity to Taiwan has reportedly angered China, claimed by Beijing in full.

Other Western nations have recently pushed for a cessation of hostilities and a diplomatic path forward.

German Chancellor Olaf Scholz publicly pushed for de-escalation in the South China Sea, insisting on a peaceful deal in line with international law.

Amid the hostilities, China has also called for "cooperation between relevant countries that is conducive to peace, stability, and development in the region."

Location

The South China Sea covers 3.5 million square kilometres and carries around a third of the world's shipping.

It is widely seen as an economic and geostrategic location and a vital passage for global commerce, encompassing Brunei, Cambodia, China, Indonesia, Malaysia, the Philippines, Singapore, Taiwan, Thailand, and Vietnam.

Northern neighbours like Japan and South Korea also rely on the waterway to export fuels and raw materials.

Trade passing through the vital waterway is worth an estimated $3.3 trillion, representing more than 20 percent of all global trade. Territorial disputes and security concerns remain fundamental issues.

Claims to South China Sea

The area is one of the most fiercely disputed areas in the world.

Alongside China are seven claimants in the region, including Brunei, Indonesia, Malaysia, the Philippines, Taiwan, and Vietnam.

Some disputed areas include the Second Thomas Shoal—or the Ayungin Shoal, Bai Co May, and Ren'ai Jiao—a submerged reef in the Spratly Islands.

The waterway holds abundant reserves of oil and gas, which reportedly make up the "aggravating factor" in the maritime and territorial disputes.

It is believed to hold around 11 billion barrels of oil, 90 trillion cubic feet of natural gas, and around 10 percent of the globe's fisheries.

The South China Sea's major island and reef formations are the Spratly Islands, Paracel Islands, Pratas, the Natuna Islands and Scarborough Shoal.

In 2002, China and the Association of Southeast Asian Nations (ASEAN) signed the South China Sea Declaration on the Conduct of Parties (DoC), which is said to mark "China's first acceptance of a multilateral agreement."

The dash-line

Beijing has claimed the large maritime territory in the South China Sea as part of its so-called "nine-dash line," which includes the Paracel Islands and the Spratly group.

However, this claim has been rejected in the past. In 2016, The Hague-based Permanent Court of Arbitration said the border has no legal basis under international law.

Beijing claims around 90 percent of the total area—a U-shaped area that dates back to 1947 when Beijing made the claim.

The disputed islands

China, Taiwan, and Vietnam all claim sovereignty over the more than 230 small islands and reefs in the area that together form the Spratly Islands.

The Philippines claims 53 features, Malaysia 12, Vietnam occupies 27, China 8, the Philippines 7, Malaysia 5, and Taiwan 1.

China has built artificial islands in the Spratly archipelago, including port facilities, military buildings, and an airstrip.

Another disputed area is the Paracel Islands, an archipelago of 130 islands and reefs that China, Vietnam, and Taiwan all claim. However, Beijing has controlled the region since the early 1970s.

The Philippines and China have disputed the Scarborough Shoal, an area alongside Malaysia and Brunei, which has seen a standoff between competing nations.

In 2016, the Permanent Court of Arbitration in The Hague said Beijing's claims had no legal basis after the Philippines launched the arbitration while China rejected the ruling.

UN law and Exclusive Economic Zone

Amid the disputes, in 1982, the UN pushed to establish a legal balance between the economic and security interests in the area.

In 1994, the United Nations Convention on the Law of the Sea (UNCLOS) emerged to safeguard a 200-nautical mile area. The UNCLOS reportedly extended "sole exploitation rights to coastal nations over marine resources."

The Exclusive Economic Zone (EEZ) was not intended to act as a security zone, while UNCLOS also guarantees passage rights for naval vessels and military aircraft.

Despite being signed and ratified by all the countries in the region, the interpretation of UNCLOS in the South China Sea remains highly disputed.