China is considering expanding the construction of civilian facilities on some of the South China Sea islands, and the scale of the construction depends on the threat level China faces in the region, analysts said.

"Civilian construction will increase significantly. Airports will be expanded. Airstrips on some of the islands, like the Meiji Reef and Zhubi Reef, will be lengthened," Li Jie, a Beijing-based naval expert, told the Global Times.

Much of the construction will be focused on search and rescue efforts, including providing assistance and supplies to distressed vessels, the expert said.

"China may also increase the number of defensive weapons on the islands, depending on the threat level," Li said.

Of the seven inhabited islets in the Nansha Islands, Meiji, Zhubi and Yongshu are the largest and best equipped. According to experts  from the US-based Center for Strategic and International Studies (CSIS), Meiji Reef is about 6 square kilometers, while Zhubi and Yongshu are about 4 and 3 square kilometers, respectively.

Last week, China tested two new airports on Meiji and Zhubi reefs, about 1,000 kilometers from Hainan Province. The airport on Yongshu was completed in January.

China is not the only country that reclaims land in the disputed waters. Vietnam has also reclaimed land in at least a dozen areas in the Nansha Islands, two of which were also tracked by satellite by CSIS.

Li believes some of China's islands may achieve food self-sufficiency.

"Taiping Island, which is only 0.5 square kilometers, has been able to produce a good amount of vegetables. Meiji and Zhubi could produce more. Sea water may be desalinated to produce clean fresh water," Li said.

Chinese Navy Commander Wu Shengli on Monday told visiting US Chief of Naval Operations Admiral John Richardson that China will continue construction work in the South China Sea.

Tensions have been rising especially after an arbitration tribunal in The Hague ruled that China's historic rights to resources in sea areas falling within the nine-dash line were "baseless." China firmly rejected the ruling.

Maritime 4G signals

As of Thursday, China Telecom has provided 4G signals to all seven inhabited islets in the Nansha Islands. China Mobile also built 4G base stations on Yongshu and Zhubi Reef as early as March 2015.

Statements sent to the Global Times by China Mobile's Hainan office said the company has opened more than 20 base stations in at least 13 islets and reefs in Xisha and Nansha Islands as part of the country's communications infrastructure.

"Ships passing these waters will receive a message that says 'Welcome to China' [to indicate China's sovereignty]," the statement read.

Vietnam's foreign ministry filed a protest against China in September last year after learning

China Mobile has been providing 4G signals to all seven inhabited islets in Xisha Islands since the start of 2015.

The company also constructed China's first ship-borne satellite base station on Sansha No.1, the supply ship that travels between Qinglan Harbor in Wenchang, Hainan Province and Yongxing Island in Xisha earlier this year.

The ship-borne station allows crews to make phone calls, use WeChat and conduct 4G video conferences at sea, which effectively improves the ships' communications with their headquarters, Lin Zhiyou, a China Mobile network engineer in charge of testing the ship-borne station, told the Global Times.

Yongxing Island is the largest island in Xisha, where the city of Sansha is located. Sansha is the southernmost Chinese city that has jurisdiction over Xisha, Nansha and Zhongsha Islands.

Floating nuclear power stations

China is also eyeing its first maritime nuclear power platform, and is expected to build 20 floating nuclear power stations in the future.

The floating power station will be able to provide safe and efficient power supply to remote  islands in the South China Sea, and power seawater desalination, the China National Nuclear Cooperation wrote in an article published on its official social media WeChat account on Thursday.

The article was later removed from the platform.

Liu Feng, an expert on maritime issues, told the Global Times that tourism may be another area of island development.

He said that it is possible some of the islands can host water sports, such as surfing and sailboarding.

Cruises to three islands in the Xisha Islands - Yinyu, Quanfu and Yagong Islands - are currently available under China International Travel Service's Hainan branch. The cruiseship, Beibuwan No.1, leaves Sanya, Hainan Province every Tuesday for a four-day trip.

Chen Heying contributed to this story