Vietnamese anger towards China is running at its highest level in years after Beijing deployed an oil rig in disputed waters. That's putting Vietnam's leaders in a difficult position as they calculate how far to allow public protests that could turn into demonstrations against their own authoritarian rule.
At one level, the ruling Communist Party would like to harness the anger on the street to amplify its own indignation against China and garner international sympathy as naval ships from both countries engage in a tense stand-off near the rig off the Paracel Islands in the South China Sea.
But Vietnam's government instinctively distrusts public gatherings of any sort, much less ones that risk posing a threat to public order.
And they also know that members of the country's dissident movement are firmly embedded inside the anti-China one, and have used the issue to mobilise support in the past.
Yesterday, around 100 people protested outside the Chinese consulate in the country's commercial capital, Ho Chi Minh City, watched by a large contingent of security officers.
The two nations have a history of conflict going back 1,000 years, and the streets of Vietnam's cities are named after heroes in those fights.
Yet the two countries share a Communist ideology and close economic ties, making the China-Vietnam relationship a highly sensitive topic. The latest round of tension has led to fresh and awkward questions over that relationship, normally a taboo in the state-controlled media.
"It's time for the Communist Party of Vietnam to reconsider all its policy towards Beijing ... Vietnam should immediately abandon Beijing as an economic and a political model," Huy Duc, one of Vietnam's best-known bloggers wrote in a recent post. "Hopefully, the drilling rig 981 incident will awaken the Communist Party of Vietnam to be on the side of the people and drive out the Beijing expansionists."
A statement widely circulated on Facebook and dissident blogs called for protests today in Hanoi outside the Chinese embassy and a Chinese cultural centre in Ho Chi Minh City. In past years, authorities have only allowed anti-China demonstrators to walk around a lake in downtown Hanoi.
"Facing the danger of Chinese aggression appropriating the sacred East Sea, the source of livelihood of the Vietnamese over generations, we are determined not to compromise," according to a statement posted alongside the protest call that used the Vietnamese term for the South China Sea.
"We cannot continue to compromise and be vile and sinful to our heroic ancestors and feel ashamed before our future generations," it said.
The last time there was a flare-up in the South China Sea in 2011, anti-Chinese protests lasted weeks, and some protesters voiced slogans against the government. Authorities used force to break them up.
"The state is in a truly difficult position," said Jonathon London, an expert on Vietnam at Hong Kong's City University. "By expressing its stern objections to China, it also invites expressions of dissent from Vietnamese that can take multiple forms. Certainly there is some overlap between those who want to express their anger at China, and those who are calling for basic reforms."
Vietnam's first response to the rig's deployment close to the Paracel Islands was to send ships to try to stop the rig from starting drilling, and demand Beijing withdraw.
Yet it can't afford to do anything that would severely rupture ties with Beijing because it is the country's largest trading partner.
Watch: US senators: China sea actions 'deeply troubling'
US lawmakers condemn China's 'harassment' of South China Sea neighbours
International pressure is growing on China and Vietnam to resolve their dispute over contested South China Sea waters peacefully.
Several US lawmakers criticised Beijing on Friday for its "deeply troubling" actions after it announced last week it would move an oil drilling rig into contested waters.
They also urged passage of legislation that seeks peaceful solutions to rising maritime tensions.
Several collisions in the area have been recorded between Chinese and Vietnamese ships, with each side blaming the other for the incidents.
"China's recent movement of an oil drilling rig escorted by military and other ships into disputed waters in the South China Sea off the coast of Vietnam - and the subsequent aggressive tactics used by Chinese ships, including the ramming of Vietnamese ships - is deeply troubling," the senators said.
"These actions threaten the free flow of global commerce in a vital region."
The bipartisan group of six lawmakers, led by Senate Foreign Relations Committee chairman Robert Menendez, are sponsors of a non-binding resolution introduced in April that condemns the use of force and advocates a peaceful diplomatic resolution of territorial and maritime claims.
In November China set up an "air defence identification zone" over the East China Sea that covered contested islands claimed by it and Tokyo. The senators warned that the zone and Beijing's "harassment of Japanese vessels around Japanese-administered territory in the East China Sea all raise serious questions about China's approach to regional security".
US Secretary General Ban Ki-moon urged China and Vietnam to exercise "utmost restraint" and resolve their dispute peacefully.
Agence France-Presse, Associated Press