The Vietnamese government has warned against the use of the internet to attack the Communist Party, amid swirling rumours of divisions and infighting in the run-up to the party congress in January.
It condemned what it called “toxic activity” on social media, which has become a forum for political comment unimaginable during the previous decades of Communist Party control.
Commentators from inside and outside the country have taken to the web to critique and lampoon an opaque political system that remains a taboo subject for the state controlled media.
“These pages are most distorting and talking bad about our party’s leaders, government and policies,” said Truong Minh Tuan, the deputy minister of information and communications, in a post on the government’s Facebook page.
“We expect more such bad pages appearing around the congress and election,” he said.
The government has already tried to intimidate its most persistent critics with selected arrests and violent street attacks by plainclothes vigilantes acting as proxies for the security forces.
It’s a sign of the acute political sensitivity of party bosses as they prepare to select new top leaders for party and state after the congress at the end of January.
Many observers see a power struggle behind the scenes, between a faction led by the ambitious prime minister, Nguyen Tan Dung, and those in the camp of the party general-secretary, Nguyen Phu Trong.
Mr Dung is seen as more favourable to economic reform and a closer alignment with the United States, while conservative factions remain closer to China.
Allegations of corruption against leading players and their families are particularly unwelcome. Rival politicians are often suspected of using innuendo and smears to advance their own cause in the run-up to major transfers of power.
The repression of dissident voices has gone ahead despite the risk of alienating key trading partners such as the US and the EU.
Violent attacks on well known bloggers and dissidents, and the arrest of the human rights lawyer, Nguyen Van Dai, have led to a wave of protests from overseas.
The US ambassador, Ted Osius, is the latest senior diplomat to express his dismay at the suppression of dissent.
“This disturbing trend, at this time, threatens to overshadow Vietnam’s progress on human rights in recent years,” he said in a statement released to the media.
“I urge the Vietnamese government to investigate reports of these assaults immediately and to hold accountable any officials responsible,” he said.
The party congress will be watched closely for signs of the future direction of a country that is struggling to balance relations between China and the United States, and to maintain its monopoly of power in the internet age.
Some analysts expect the prime minister, Mr Dung, to emerge as the new general-secretary of the party.
But despite his association with economic reform, few expect an immediate easing of repression or a more tolerant attitude to government critics.
China remains the model most firmly fixed in the minds of party apparatchiks.
And the message from north of the border is that the party has no reason to give ground to its critics inside or outside the country.