China´s navy chief warned his US counterpart encounters between their forces could spiral into conflict, state media reported, two days after a US destroyer sailed close to Beijing´s artificial South China Sea islands. “If the US continues to carry out these kinds of dangerous, provocative acts, there could be a serious situation between frontline forces from both sides on the sea and in the air, or even a minor incident that could spark conflict,” Xinhua  Wu said.

Beijing insists it has sovereign rights to nearly all of the South China Sea, a strategic waterway through which about a third of all the world´s traded oil passes.The disputed waters — also claimed in part or in whole by Vietnam, Malaysia, the Philippines, Taiwan and Brunei — have also become the stage for a tussle for regional dominance between Beijing and Washington, the world´s two largest economic and military powers.

For decades, the United States has dominated Asian waters, with its colossal navy roaming vital waterways with impunity. The US navy has been both domineering and benign for its allies, supporting armed interventions and maintaining access to military bases across continents, as well as protecting maritime arteries of trade against state and no-state predators.

With as much as 90 percent of global trade conducted through maritime routes, all countries have an interest in ensuring freedom of navigation across international waters. And for a long time, the US and its allies have served as the de facto guarantor of unimpeded access to global sea lines of communications.

The Soviet Union’s earlier efforts to challenge American naval supremacy ended up bankrupting its fragile economic base, paving the way for its eventual collapse in the late 20th century.

After criticizing the U.S. patrol earlier in the week for taking a “reckless action,” China’s Foreign Ministry said the tribunal’s ruling “is null and void, and has no binding effect on China.”

“With regard to the issues of territorial sovereignty and maritime rights and interests, China will not accept any solution imposed on it or any unilateral resort to a third-party dispute settlement,” the ministry said. The strategies by the two close allies, the U.S. and the Philippines, pressures China to define its vague claims to most of the South China Sea more clearly under international law, some analysts say.

“The U.S. and the Philippines have been effectively acting as a tag team,” said Richard Javad Heydarian, an academic who specializes in regional security at De La Salle University in Manila. “The Philippines has overcome a very difficult hurdle by clearing the jurisdiction issue.”

China claims by far the largest portion of territory – an area defined by the “nine-dash line” which stretches hundreds of miles south and east from its most southerly province of Hainan. With as much as 90 percent of global trade conducted through maritime routes, all countries have an interest in ensuring freedom of navigation across international waters. And for a long time, the US and its allies have served as the de facto guarantor of unimpeded access to global sea lines of communications.

Beijing says its right to the area goes back centuries to when the Paracel and Spratly island chains were regarded as integral parts of the Chinese nation, and in 1947 it issued a map detailing its claims. It showed the two island groups falling entirely within its territory. Those claims are mirrored by Taiwan.

The defining characteristic of the South China Sea and a significant source of tensions in the region are the competing legal claims of territorial sovereignty over its islands. The United Nations Convention on the Law of the Sea (UNCLOS), which was concluded in 1982 and came into force in 1994, was meant to establish a series of legal measures and laws on the economic rights of nations based on their territorial waters and continental baselines. This is encompassed in the Exclusive Economic Zone (EEZ), a 200 nautical mile area that extends from the baseline of the coastal nation and gives the nation sole natural resource exploitation rights within the zone.

Vietnam hotly disputes China’s historical account, saying China had never claimed sovereignty over the islands before the 1940s. Vietnam says it has actively ruled over both the Paracels and the Spratlys since the 17th Century – and has the documents to prove it.

The other major claimant in the area is the Philippines, which invokes its geographical proximity to the Spratly Islands as the main basis of its claim for part of the grouping.

Both the Philippines and China lay claim to the Scarborough Shoal (known as Huangyan Island in China) – a little more than 100 miles (160km) from the Philippines and 500 miles from China.

 President Obama has been under increasing pressure from, for example, Arizona Senator John McCain to be more assertive in the South China Sea.

The United States is preparing to maneuver naval warships and aircraft close to China’s artificial islands in the South China Sea, in what would be the Obama Administration’s toughest response yet to Beijing.

Reportedly, the White House is readying plans to send warships within twelve nautical miles of several of the islands—a move that China claims would be an illegal violation of its sovereignty. Citing a U.N. treaty, the United States argues that man-made outposts cannot be construed as legitimate territory.

China has also said it had every right to set up an Air Defence Identification Zone (ADIZ) in the South China Sea but that current conditions did not warrant one.

ADIZs are used by some nations to extend control beyond national borders, requiring civilian and military aircraft to identify themselves or face possible military interception.

During the P8-A mission, the pilot of a Delta Air Line flight in the area spoke on the same frequency after hearing the Chinese challenges, and identified himself as commercial. The Chinese voice reassured the pilot and the Delta flight went on its way, CNN said. US defence secretary Ash Carter warned that further “freedom of navigation” operations in the region were planned. “We will fly, sail and operate wherever international law permits,” he told a congressional hearing. China’s military buildup in the South China Sea – including the construction of a 3km runway capable of supporting fighter jets and transport planes – has become a major source of tension between Beijing and Washington.

China claims most of the South China Sea, one of the world’s busiest sea lanes, although Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims. Beijing says the islands will have mainly civilian uses as well as undefined defence purposes.

The Permanent Court of Arbitration – which is more than a century old and based in The Hague – ruled that it did have jurisdiction on the issue.

Manila insists the United Nations Convention on the Law of the Sea, which the Philippines and China have both ratified, should be used to resolve the bitter territorial row over isolated reefs and islets, which has triggered growing international alarm.

US researchers have found that since March 2014, China is building artificial islands atop 7 reefs and atolls in the Spratly archipelago of the SCS, the sovereignty of which is being disputed by   Taiwan, Malaysia, Brunei, the Philippines and Vietnam. The seven identified by them are – Subi reef, Hughes reef, Garen islands, Jhonson South reef, Cuarteron reef, Fiery Cross reef and Mischief reef. The US analysts have further revealed that the PRC in this way could create about 3,000 acres of new sovereign territory. and felt that once these artificial islands become operational, China can assert its sovereignty over the territorial airspace and waters.

On its part, China is denying that it is claiming such sovereignty. The PRC Foreign Minister Wang Yi said (ASEAN Regional Forum, Kuala Lampur, August 5, 2015) that “China’s construction of the islands, mainly to improve the working and living conditions of personnel there and for public good purposes, has already stopped.” Despite this, recent US satellite images taken on September  3 and 8, 2015, have shown that China is fast completing construction of an  air strip each in Subi and  Fiery Cross reefs and possibly a naval base in the Mischief reef.

It has to be recognized that the Chinese and US perceptions of the freedom of navigation principle in the United Nations Convention on the Law of the Sea, not yet ratified by it, are different.  Washington believes that the US ships can sail in both the 200-nautical mile exclusive economic zones (EEZs) and the 12-nautical mile territorial seas without obtaining the permission of the coastal states. The PRC’s stand is that foreign navies will have to obey rules of “innocent passage” even in the 200-nautical mile EEZ, and require prior permission to enter the 12-nautical mile territorial sea. This being so, there seems to be no unanimity among the ASEAN nations on the freedom of navigation principle.  Malaysia agrees with the Chinese view on the EEZ and Vietnam   shares the PRC’s definition of the territorial sea.

Evaluating broadly the likely shape of the current China-US tussle on the artificial islands issue, it can be said, that the final picture may not be pessimistic one. It needs to be admitted at the same time that any misjudgment or miscalculation by the two powers may result in unexpected scenario.

US scholars have assessed that President Xi Jumping’s visit to US in September 2015 was not only very smooth, but it also contributed to building by the two countries of   a strong strategic framework, and that the two are now embarking on a path of cooperation instead of one of confrontation.

Their Chinese counter parts seem to think on the same lines. The PRC State media opinions see Xi’s US visit as having contributed to a series of “early harvest” in many aspects, such as the expansion of pragmatic cooperation and effective control of divergences. Thus becoming clear is the keenness of each side to sustain the improvement in bilateral relations; in such atmosphere, there are chances of China and the US agreeing on a face saving formula, in order to deescalate tensions on the islands issue.

It may not come as surprise if the two reach an understanding on the ‘innocent passage’ of their naval vessels close to their respective territories; the PRC in particular may stop insisting on its condition that foreign vessels need prior permission to enter its perceived territories.

 “We are not neutral when it comes to adherence to international law. We will come down forcefully on the side of the rules,” Daniel Russel, Assistant Secretary of State for East Asian and Pacific Affairs, asserted during a speech delivered at the Center for Strategic and International Studies.

 Washington has also repeatedly urged all nations to stop land reclamation efforts but the US is especially critical of China, claiming that Beijing’s endeavors on the Spratly Islands could lead to the militarization of the area and would hence undermine regional stability and security. Looking beyond the current China-US tussle on the artificial islands issue, it can be said that though the region is getting benefits from multilateral efforts towards achieving  economic integration  , its instability seems certain as there may be no quick end to the territorial contest taking place in the SCS.  The implications for the future shape of geopolitics in East Asia can thus be clearly understood.

Beijing has insisted that it is the US’ meddling in the Asia-Pacific, including its deepening military ties with Japan, that could jeopardize regional security. When it comes to rules, the United States is notably one of the few countries in the United Nations that has not signed onto the UN Law of the Sea convention.