south china sea borders

South China Sea: Territorial disputes leave 6 separate border claims

   Where we are in the world

The South China Sea is a body of water tucked between China, Vietnam, Malaysia, Indonesia, Philippines and Taiwan. The Sea is vitally important to all countries and has recently been the source of significant border tensions stemming from China’s claim to the vast majority of the area. The other countries bordering the South China Sea have rebuked China’s claim – dubbed the “9-dash line”.

For other maps on border disputes, see posts on the Kaesong Industrial Zone in South/North Korea and Dadra and Nagar Haveli and Daman and Diu!

See the interactive Google Map at the bottom of the post!
Source: Imgur

   Three key facts about this map

The South China Sea is an incredibly important trading route

One of the main reasons why the South China Sea is the center of these ongoing border disputes is because of its strategic importance to international shipping routes. It is estimated that 1/3 of global trade passes through the Sea. For China, Japan, South Korea, Vietnam, Taiwan, Philippines and Malaysia, the South China Sea is vital to connect to the Indian Ocean via the Straits of Malacca by Singapore, Malaysia and Thailand. These Straits connect the Asian markets to India, the Middle East/Africa, and Europe (through the Suez Canal).

The estimated value of trade flowing through the South China Sea is about $5 trillion per year. In 2016, it was reported that China was one of the most-reliant with 64% of its trade passing through the Sea. This fact can help explain why China has been taking aggressive moves to stake its claim in the region.

Along with foreign trade there is reportedly significant oil & gas reserves in the South China Sea, marking another important element to these ongoing border claims.

China has built artificial islands that contain fully militarized bases

As part of its aggressive moves to stake its claim in the South China Sea, China has been building fully militarized bases on several small islets in the Spratly Islands in the center of the Sea. Over the past decade, the military has been reclaiming land and building large artificial islands that often contain air bases/runways along with anti-ship and anti-aircraft missile systems.

Islands with significant Chinese military presence include:

  • Cuarteron Reef
  • Fiery Cross Reef
  • Gaven Reefs
  • Johnson Reef
  • Mischief Reef

See the interactive Google Map below and zoom in on examples of the Chinese bases.

Example of Cuarteron Reef land reclamation efforts by the Chinese military, building up a significant base including a large airport/runway for military aircraft

China has been aggressive recently in staking its claim on the islands

Leveraging its relatively new military bases on islands in the South China Sea, China has been aggressively pushing back on any foreign interference in the region.

The US military has regularly maintained a presence in the region due to its ties with Taiwan (and the Philippines). China routinely rebukes any US interference in the region. One incident involved a US P-8A Poseidon flying over the Spratly Islands (over Fiery Cross Reef) on a recoinnaissance mission. The Chinese military issued several warnings to the passing US aircraft claiming that it was intruding on their sovereign territory. Fortunately, no action was taken.

Another incident recently occurred in 2023 when a Philippines military aircraft flew over the Spratly Islands and was issued a “stern warning” from the Chinese military to “leave immediately”. The Philippines aircraft was travelling to a Philippines-occupied islet, Thitu Island, and was one of several incidents where China claimed incursions onto “their territory”.


   Additional links and sources

  • Overview of territorial border claims (link, published in 2022)
  • Article on China’s fully-militarized islands in the South China Sea (link, published in 2022)
  • Recent incident of China taking harder stances in the Spratly Islands (link, published in 2023)
  • Trade traversing the Sea (link, published in 2017, updated in 2021)

Have you heard of this territorial dispute before?


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