A violent and prolonged attack on female environmental activists at a private home in Ho Chi Minh City has spread alarm among civil society campaigners.
The brazen nature of the attack, and its subsequent posting on Facebook, seems designed to send a warning to government critics.
The video shows unidentified assailants repeatedly kicking and punching Le My Hanh and two of her female friends at one of their homes in the city.
Hanh was knocked unconscious and sustained severe bruising after being repeatedly kicked in the face.
The attack came shortly after she had arrived in the city from her home in Hanoi, where she was also attacked last month while attempting to film a report by West Lake.
Hanh has received regular threats from pro-government vigilantes following her involvement in the campaign to demand government accountability for the Formosa toxic leak off the central coast last year.
The violence of the latest attack, on activists in their own homes, takes the campaign of intimidation to a new level.
At least five thugs broke into the apartment, including two women, and sprayed Hanh and her friends with pepper gas before beginning the attack.
The assault was filmed by a man named Phan Hung who posted the video on his own Facebook page.
The assailants repeatedly called the women “reactionaries” as they landed their kicks and punches, a word used by the Communist party to demonise pro-democracy activists.
In his post, Hung described the incident as a “welcome” for Hanh to Ho Chi Minh City. He threatened the same treatment for others who defamed leaders and supported what he called “three stripes”, a reference to the flag of the Saigon regime defeated in 1975.
The police have denied that Hung and the attackers worked for them and say they are investigating.
The women said they were initially told by police that their injuries were not serious enough to warrant further action.
Police commanders have frequently been accused of hiring vigilantes to carry out assaults on civil society activists.
The tactic gives them a degree of deniability, and enables them to keep up a legalistic front, while at the same time instilling fear in those bold enough to criticise government officials.