Michael Phuong Minh Nguyen, 55, a US citizen, was detained in July 2018 while travelling in Vietnam with two activists, who were also arrested.
His lawyer, Nguyen Van Mieng, said: “It’s such a long sentence. Michael admitted guilt at the trial and asked the jury to reduce his sentence so that he could soon reunite with his family.”
The three were accused of preparing for an armed protest and attacks government buildings in Hanoi and Ho Chi Minh City with petrol bombs and slingshots, state-run VnExpress reported.
The US is a key strategic ally to Hanoi, which is worried about an increasingly assertive China to its north and Beijing’s expansionism in the South China Sea. Several US citizens who have offended the Vietnamese authorities have previously been allowed to leave the country without fanfare.
Nguyen half-day trial in Ho Chi Minh City ordered him to leave the country after completing his sentence, a defence lawyer said.
Tran Long Phi was jailed for eight years and Huynh Duc Thanh Binh 10 years for the same charge.
“The sentence for the defendants is too harsh,” lawyer Nguyen Van Mieng told the media.
The authorities say they are looking for a fourth man connected with Nguyen, who is on the run.
After leaving Vietnam in 1975 as a child, Nguyen settled in the US among more than 1 million refugees who fled when the triumphant communists.
Many exiles tried to mobilise against the communist government from afar, but Nguyen’s family denies he had any involvement with any such movement.
Vietnam has increasingly jailed its critics since a new administration took power in 2016, with an estimated 130 political prisoners being held, according to some estimates.
A 2018 cybersecurity law gave the authorities unprecedented powers to monitor online content and has been criticised by the US, EU, UN and human rights groups.
The bill requires internet companies like Facebook and Google to hand over user data and remove material from their sites when requested by the government.
“We are disappointed by today’s verdict,” said the United States embassy in Hanoi. “We will continue to raise our concerns regarding Mr Nguyen’s case, and his welfare, at all appropriate levels.”
Michael Nguyen fled Vietnam as a child in 1975. Picture credit: Flickr