China and Vietnam are continuing to clash over a maritime sovereignty dispute despite diplomacy and calm being displayed by other claimants to the same sea.
The Communist neighbors talk regularly about their differences party-to-party as well as through diplomatic channels. Around the rest of the contested South China Sea, claimed by six governments total, other countries have largely avoided openhanded spats over the past three years.
Yet a new dispute erupts between China and Vietnam about once a year. They're locked in another one now over energy exploration in an area in the sea that both countries call their own.
The two countries continue to spar because of decades, if not centuries, of distrust coupled with material ambitions in the 3.5 million-square-kilometer sea, experts say.
"I think the big picture on China-Vietnam relations is that they would go for diplomacy and they would go for hardball games," said Eduardo Araral, associate professor at the National University of Singapore's public policy school. "It's a very long love-hate relationship between China and Vietnam."
In the most recent clash between the two countries, a Chinese coast guard vessel has been patrolling since June 16 around a seabed tract about 352 kilometers off the coast of southeastern Vietnam, according to the Asia Maritime Transparency Initiative under the Center for Strategic & International Studies think tank.
Those patrols are "centered on" oil and gas Block 06-01 northwest of Vanguard Bank on the Vietnamese continental shelf, the initiative says. It also falls within China's nine-dash line. China uses the line to demarcate its claims to about 90% of the sea, which is rich in fossil fuel reserves as well as fisheries and marine shipping lanes.
Chinese maritime militia ships and multiple merchant marine vessels joined the coast guard vessel, geopolitical research organization Stratfor Worldview says in a July 16 report. Their presence led to a "standoff", Stratfor adds. Vietnam eventually asked the Chinese exploration vessel and coast guard ships to leave.
Vietnamese are "nationalistic" overall and remember colonization by China, Araral said. China colonized what are now parts of northern Vietnam more than a millennium ago. Vietnam repelled modern China in a border war in the 1970s.
Vietnamese now believe the South China Sea's Paracel Islands should also be theirs. China has controlled that archipelago since 1974.
Leaders in Hanoi are trying to balance their foreign policy to avoid dependence on China, despite their Communist linkage, said Carl Thayer, Southeast Asia-specialized emeritus professor with the University of New South Wales in Australia.
After China and among the South China Sea claimant nations, Vietnam is the second most active seeker of oil, gas and the small expansion of its holdings on small islets.
Vanguard Bank disputes
Vanguard Bank has "frequently been at the heart of Vietnam and China's long-standing maritime tensions, with Beijing trying to limit or block Hanoi from exploring in what it considers disputed territory," Stratfor Worldview says. That tension flared up a lot in the 1990s, Thayer said.
Last year, Spanish driller Repsol suddenly quit a Vietnamese-approved energy exploration project at Vanguard Bank, apparently under pressure from China, foreign media reports and political experts said at the time. Vietnam still maintains outposts there.
The two countries never resolved their 2018 dispute, Thayer said. "Vietnam stood down and they didn't buy Chinese acquiescence then to solve this matter," he said.
Wider sovereignty dispute
A string of other incidents has shaken the two countries over the past five years. In 2014, a Chinese oil rig touched off a boat-ramming incident in the South China Sea and deadly anti-China riots in Vietnam.
In March this year, search-and-rescue officials in Hanoi said a Chinese vessel had rammed a Vietnamese boat near Discovery Reef east of Vietnam.
Vietnam's Communist Party normally sends a special envoy to China for talks over these flaps, Thayer said.
"I think they need to find areas with mutual interest to cool off the face-off," said Andrew Yang, secretary-general of the Chinese Council of Advanced Policy Studies think tank in Taiwan. "I think they will do this, because they've got enough trouble already and they don't want to create another one."
China, the strongest player in the six-way sovereignty dispute, is already using trade and investment incentives - backed by the world's second biggest economy - to ease its sovereignty disputes with Brunei, Malaysia and the Philippines. Vietnam has seen an influx of Chinese tourists.
But "diplomacy will probably fail" to solve maritime sovereignty issues, Araral said.