Vietnamese political blogger Nguyen Huu Vinh, left, and his assistant Nguyen Thi Minh Thuy, at their trial in Hanoi on March 23, 2016. (Handout/Reuters/Doan Tan/Vietnam News Agency)

NGUYEN HUU VINH is a Vietnamese blogger better known by the name Ahn Ba Sam. He’s no radical; he was once a police officer in the Ministry of Public Security in Hanoi, later a private investigator, and is the son of a former Vietnamese government minister who served as ambassador to the Soviet Union. After leaving the police, Mr. Vinh started several popular blogs that provided links to articles about social, political, economic and cultural issues in Vietnam, drawing from state media and from activists.

The blogs were too much for Vietnam’s authoritarian rulers, who control the major news outlets and restrict speech, association and religion. In May 2014, Mr. Vinh was detained, along with his assistant, Nguyen Thi Minh Thuy. They were held in prison throughout last year, without trial, a period when Vietnam was in the final throes of negotiating with the United States over the Trans-Pacific Partnership trade deal.

Then, on March 23, the bloggers were put on trial, accused of “abusing rights to freedom and democracy to infringe upon the interests of the state.” Prosecutors said some of the articles on their site had “untruthful and groundless contents” that tarnished the country’s image. Mr. Vinh was sentenced to five years in prison and his assistant to three years. Both insisted at the one-day trial they were innocent. The presiding judge thought otherwise, and said the articles they had posted “present a one-sided and pessimistic view, causing anxiety and worry, and affecting people’s confidence” in the Communist Party and the government, and “go against the interests of the nation.”

Vietnam has previously prosecuted bloggers and discourages dissent in other ways, too. According to Human Rights Watch, last year at least 45 bloggers and rights activists were beaten by plainclothes agents. Late last year, the state’s thugs badly beat up Nguyen Van Dai, a prominent human rights activist and lawyer. He led a workshop on human rights in early December in Nghe An province and was assaulted by plainclothes goons. On Dec. 16 in Hanoi, he was formally arrested and thrown into solitary confinement. His wife, Vu Minh Khanh, told us he has not been allowed visitors or contact with his family. He was told his arrest was for “conducting propaganda against the state.” He was fighting for a freer and more open Vietnam.

We have been hopeful that Vietnam’s inclusion in the Trans-Pacific Partnership trade deal would nudge its rulers toward greater openness and tolerance, but Ms. Khanh said the human rights situation is “dreadful” and growing worse. Even though the Trans-Pacific Partnership is not explicitly about democracy, the United States ought to bring up human rights at every opportunity, to drive home the point that blogging and human rights workshops are consistent with an open and free society. President Obama, due to make his first visit to Vietnam next month, ought to carry the message personally. Vietnam’s besieged bloggers and human rights defenders would find it encouraging.