On Saturday 18 April 2020, China’s Ministry of Civil Affairs announced that the State Council of China had approved two new administrative divisions under Sansha City, an earlier administrative unit created in 2012 to encompass the South China Sea. While nominally a “city,” Sansha encompasses 2 million square kilometers and more than 200 features. The two districts — named Xisha and Nansha — use the Chinese names for the disputed Paracel and Spratly Islands, respectively, and correspond to those features. China claims the entirety of the Paracel and Spratly Islands under its capacious nine-dash line claim.

Territorial disputes in the South China Sea involve both island and maritime claims among several sovereign states within the region, namely Brunei, the People's Republic of China, Malaysia, the Philippines, and Vietnam. The 2002 ASEAN-China Declaration on the Conduct of Parties in the South China Sea states that the parties undertake to exercise self-restraint in the conduct of activities that would complicate or escalate the disputes in the area. Although reclamation works and the construction of installations and structures on occupied features would seem to be inconsistent with this provision, China, Malaysia, the Philippines and Vietnam have all undertaken such activities on the features they occupy and control in the Spratly Islands.

The source of the South China Seas dispute is traceable to the 1951 San Francisco Treaty, which failed to stipulate possession of the Spratly islands when Japan lost its title to them after defeat in the Second World War (art. 2 (f): "Japan renounces all right, title and claim to the Spratly Islands and to the Paracel Islands"). The chain of 200 islets, coral reefs and sea mounts that constitute the Spratly and its northern extension the Paracel islands spread across 250,000 square kilometres of the South China Sea, a vast continental shelf that constitutes a potentially rich source of oil and natural gas. The Spratly’s contested ownership developed into an international conflict when from the mid-1970s a number of claimants began extracting resources from the seabed contiguous to their Exclusive Economic Zones (EEZ). China and four ASEAN states Brunei, Malaysia, the Philippines and Vietnam all laid claim and/or occupied part of the islands in the South China Sea.

A significant aspect of the territorial dispute in the South China Sea concerns China's construction in the area, particularly in the past few years. China has engaged in large-scale land reclamation activities in seven reefs (Fiery Cross Reef, Johnson South Reef, Cuarteron Reef, Gaven Reef, Hughes Reef, Mischief Reef and Subi Reef) in the disputed Spratly Islands area of the South China Sea. These projects have created seven new artificial land masses in the Spratlys, see for some examples the following articles: Massive island-building and international law and What China Has Been Building in the South China Sea.

What legal effect, if any, will these projects have on the broader Spratly Islands and South China Sea territorial and maritime disputes? China claims "indisputable sovereignty over the islands in the South China Sea and the adjacent waters and jurisdiction over the relevant waters as well as the seabed and subsoil thereof," consistent with its maps showing nine line segments encircling most of the South China Sea and almost all of the Spratly Islands, the so-called 'nine-dash' line. China's latest lawfare approach involves shifting away from the (universally not recognized) “nine-dash line” claim to a narrower “Four shas (4S)” (Chinese for four sands) claim that more tightly connects the four contested island groups of Pratas Islands, Paracel Islands, Spratly Islands, and Macclesfield Bank. Beijing seemingly now wants to make the legal and diplomatic case that the “Four shas” are China’s historical territorial waters, and part of its extended continental shelf and 200 nautical mile Exclusive Economic Zone (EEZ) — despite not offering any new substantive legal arguments or historical evidence to back up the new claim.

China's land reclamation activities have been met with protest from several of the interested states, particularly the Philippines, the United States, Vietnam and Indonesia. China has proposed joint development as a provisional measure before settlement of sovereignty disputes. Sound in principle, most other claimants consider the presumption the nine-dash line would be the starting point of negotiations for joint development as fundamentally unfair. That line contradicts a cardinal principle of UNCLOS, to which all claimants are parties, namely that “the land dominates the sea”, so a coastal state can claim maritime zones based only on land over which it has sovereignty.

The United States has sought to uphold freedom of navigation and support other nations in Southeast Asia that have been affected by China’s assertive territorial claims and land reclamation efforts. According to the United States, countries should have freedom of navigation through EEZs in the sea and are not required to notify claimants of military activities; the United States encourages all claimants to conform their maritime claims to international law and challenges excessive maritime claims through U.S. diplomatic protests and operational activities. The US has long opposed China's actions but not called them illegal until now. China, which has been building military bases on artificial islands in the area for years, said the US "deliberately distorts facts and international law".