China held what has been widely characterized as upbeat talks this year with Brunei, the Philippines and Vietnam even though all three contest Chinese claims to a vast, resource-rich ocean. The communist leadership, meanwhile, fortified some of the sea's tiny islets, also disputed, and warned outside powers such as the United States to stay out.
Observers expect Beijing to continue on this course in 2019, extending its military and territorial lead in the South China Sea, Asia's biggest maritime dispute, without inflaming anyone to a point where Western allies escalate their challenges.
"There are a lot of things that have happened this year that I think we can use to sort of project what we see next year," said Collin Koh, a maritime security research fellow at Nanyang Technological University in Singapore. "We'll still see these parallel movements side by side."
China claims about 90 percent of the 3.5 million-square-kilometer sea that stretches from Singapore to the southern tip of Taiwan. Brunei, Malaysia, the Philippines, Taiwan and Vietnam call all or parts of the same fisheries-rich sea their own. Since 2010 Beijing has upset the others by landfilling islets, placing military hardware on some and increasing its civilian presence.
The United States does not claim the sea but seeks to ensure the waters remain open to freedom of navigation.
In November, Chinese officials signed a deal with the Philippines to jointly explore the South China Sea's valuable oil or gas reserves. They touched on the same idea that month with Brunei. China separately gave development aid to the Philippines and suggested maritime cooperation with Vietnam.
Vietnam and Philippines were outspoken critics of Chinese expansion before China stepped up dialogue in 2016. Poorer than China, they benefit from its economic help.
"Maritime Southeast Asia by and large, I think, we are wary of China, including Duterte's Philippines although Duterte made a great show of friendship for [Chinese president] Xi Jinping during the state visit earlier this year," said Alan Chong, associate professor at the S. Rajaratnam School of International Studies in Singapore.
President Rodrigo Duterte has gotten along with China since taking office in 2016, culminating in President Xi's visit in November.
Vietnam will work with China as well as other powers, said Trung Nguyen, international relations dean at Ho Chi Minh University of Social Sciences and Humanities. Vietnamese and Chinese vessels rammed one another over a Chinese oil rig in 2014. They also engaged in deadly clashes in 1974 and 1988.
"I think that [other] countries also feel that if Vietnam can enhance its capabilities, it's good for the security of the whole region, because Vietnam is one of the few countries in the region that can have a lot of experience dealing with China," Nguyen said.
Code of conduct
Deals with individual Southeast Asian states ease pressure on China to work with the 10-member Association of Southeast Asian Nations bloc on a maritime code of conduct that would help reduce the risk of mishaps, maritime analysts believe.
They agreed to start talks toward a code in 2017 but reached no deal this year with no immediate prospects for a breakthrough in 2019.
China wants to continue state-to-state talks and island construction projects first in case the code restricts its activities, maritime scholars say. China is developing tourism in the Paracel archipelago. It parked military aircraft and possibly missiles on its holdings in the Spratly island chain this year, per data from a U.S. think tank initiative.
"China's strategy in terms of this code of conduct is to make it seem like China is willing to be making it look like there's progress toward a code of conduct but to drag it out as long as possible," said Jonathan Spangler, director of the South China Sea Think Tank in Taipei.
Western allies will do more exercises in or around the sea next year but without a sustained, unified front that would push China into conflict, scholars say.
"There might be forces or ships around that area, but they may not be very close, so I would see more naval activities but [they] may not trigger conflict at sea," said Alexander Huang, strategic studies professor at Tamkang University in Taiwan.
Ships from Japan, Australia and Western Europe ventured into peripheral parts of the sea this year. U.S. warships have entered more regularly. In September, one nearly collided with a Chinese naval ship.
In 2019, domestic issues will consume leaders in many of those countries, limiting any coordination at sea, Chong said.
Chinese national defense spokesperson Ren Guoqiang said in September via the official Xinhua News Agency that the sea "is not a stage for certain countries to present their show."
China cites historical records to back its claim to maritime sovereignty.