A court in Vietnam’s Ho Chi Minh City on Monday convicted three men, one of them an Australian citizen, on charges of engaging in terrorist activities, sentencing them to prison terms of from 10 to 12 years, Vietnamese sources said.

Chau Van Kham, Nguyen Van Vien, and Tran Van Quyen were arrested in January and initially charged with “activities attempting to overthrow the state,” charges that were later changed to involvement in “terrorism that aims to oppose the people’s administration.”

Kham, a resident of Sydney, Australia, and member of the banned U.S.-based Viet Tan opposition party, received the heaviest sentence, attorney Trinh Vinh Phuc—who represented Kham in court—told RFA’s Vietnamese Service following the trial.

“The verdict was very harsh, and the sentence was too heavy,” Phuc said, adding that the defendants’ case could have been tried under terms that would have provided for sentences of less than 10 years on conviction.

“But [the court] still proceeded without paying attention to details that would have allowed for this,” he said.

“The verdict was handed down on the grounds that Viet Tan is a terrorist organization,” though no evidence ever was offered that the defendants’ activities and motivations had shown a terrorist intent, Phuc said.

Criminalizing rights advocacy

In a statement Monday, Viet Tan chairman Hoang Diem slammed the convictions and sentences imposed on the defendants, saying Kham had “traveled to Vietnam [only] to gain first-hand insight into the human rights situation in the country.”

”Nguyen Van Vien and Tran Van Quyen are peaceful activists,” Diem added.

“We challenge the Vietnamese government to provide any evidence linking them to ‘terrorism.’ The Vietnamese authorities are criminalizing human rights advocacy,” Diem said.

Born in 1971 in central Vietnam’s Quang Nam province, Vien had been active in environmental protection work following a massive spill in 2016 of toxic waste by the Taiwan-owned Formosa firm, the Brotherhood for Democracy said in a Jan. 25 statement.

The environmental disaster destroyed livelihoods across Vietnam’s central coast and led to widespread protests and arrests in affected provinces.

Tran Van Quyen, a social activist who also took part in the Formosa protests, was taken into custody ten days later in southeastern Vietnam’s Binh Duong province.

Politically motivated charges

In a statement on Monday, Phil Robertson—deputy Asia director for the international rights group Human Rights Watch—said that by sentencing the 70-year-old Kham to 12 years in prison, Vietnam has essentially condemned him to death.

“Given the harsh and unforgiving conditions in Vietnam’s prisons, he will face huge challenges to survive his entire sentence,” Robertson said, adding that Vietnam has now jailed Kham on “bogus, politically motivated charges that demonstrate just how fearful Vietnam is about people exercising their rights and demanding genuine democracy.”

“He should be released immediately and unconditionally, and allowed to return to his family in Australia,” Robertson said.

According to Human Rights Watch, Vietnam’s one-party communist government currently holds an estimated 138 political prisoners, including rights advocates and bloggers deemed threats to national security.

It also controls all media, censors the internet, and restricts basic freedoms of expression.