The United States said it was deeply concerned over Vietnam’s conviction and sentencing of an activist this week, calling the trend of increased arrests and harsh sentences of government critics “troubling”. A State Department statement on Friday also called on the communist government to release all political prisoners and allow all individuals to express their views freely and assemble peacefully without fear of retribution. Le Dinh Luong was sentenced to 20 years in prison and five years’ probation on Thursday after being convicted of attempting to overthrow the government. The State Department called the charge “vague” and urged the government to ensure its actions and laws, including the Penal Code, are consistent with the human rights provisions of Vietnam’s Constitution and its international obligations and commitments. Luong’s lawyer, Ha Huy Son, said the main charge against his client concerned encouraging others to join the pro-democracy Viet Tan group in exile in the United States, which Hanoi considers a terrorist organisation. Luong also participated and reportedly called on others to join protests in 2016 over pollution by a Taiwanese company that resulted in one of the worst environmental disasters in the country. Despite sweeping economic reforms over the past 30 years that opened the country to foreign trade and investment and made Vietnam one of fastest growing economies in the world, its government tolerates no challenge to its one-party rule. Amnesty International says 97 people are serving prison sentences for violating national security laws, while Human Rights Watch counts 119.