John Kerry begins a three-day trip to Vietnam Saturday, his first trip there as US Secretary of State. Accounts of the visit are sure to mention the historical significance: as a young man, Kerry served in combat during the Vietnam War and later criticized the US government for its conduct in the war. And although he has visited Vietnam before as a senator, he has never come as the most senior diplomatic representative of the United States.

And diplomacy will likely be the order of the day. Kerry will raise with the Vietnamese government concerns about its worsening record on human rights, in particular its growing crackdown on critics, but it is unclear how public his comments will be. In a country where security forces have assaulted people for attending a “human rights picnic”, brave Vietnamese activists need and expect full-throated US support of their rights.

But human rights does not appear to be the main purpose of his mission, which will center largely on improving US-Vietnam relations, in part through continued negotiation of the Trans-Pacific Partnership (TPP), a multilateral trade agreement in which Vietnam is a partner.

There are serious and legitimate questions to be raised, however, about whether this approach is appropriate, and whether the rewards of closer engagement are justified given Vietnam’s record. Labor activists, in particular, are worried about whether the TPP will require that Vietnam improve its atrocious record on labor rights before it receives any benefits.

Vietnam remains today what it has been for most of the last four decades: a one-party state. Its 90 million citizens are ruled by an unelected government subordinate to the Politburo of the Communist Party. Criticism of government or party, or exposing corruption or poor governance, frequently lands a citizen in jail. Independent trade unions, media companies, and unsanctioned houses of worship are all illegal. Even launching a campaign on Facebook to free your own brother can land you fifteen months in prison.

The Vietnam government’s crackdown on free expression has intensified in recent years, Detainees are often held incommunicado for long periods and subjected to torture or other mistreatment in pretrial detention, and then prosecuted in politically controlled courts before receiving long prison sentences. At least 63 political prisoners have been convicted for free speech acts in 2013 this year, an increase over the 40 cases from 2012. Vietnam now has at least 150 political prisoners in custody and likely more.

Human Rights Watch has written to Secretary Kerry about these issues, urging him to speak loudly on human rights issues. So have over 50 members of the U.S. Congress. For the sake of the people of Vietnam, he should take heed.