Among other things, the letter said the U.S. should note that Vietnam's government is still silencing dissidents, repressing religion and violating the rights of ethnic and religious minorities in the country.

Rep. Ed Royce (R-Calif.), one of the letter's signatories, said it is significant that top committee members called for these changes to the Vietnam report. He said he hopes State moves up Vietnam as a "country of particular concern," a status that would require State to more actively work on improving the situation there.

Reps. Chris Smith (R-NJ), Zoe Lofgren (D-Calif.) and Loretta Sanchez (D-Calif.) also signed the letter to Clinton.

Lofgren, Sanchez, Wolf and Rep. Gerry ConnollyGerald (Gerry) Edward ConnollyLights, camera, SCOTUS Bipartisan pair wants commission to oversee Iran deal Dem lawmaker warns of 'political and moral limitations’ to working with Trump MORE (D-Va.) wrote a separate letter to David Shear, the U.S. ambassador to Vietnam, asking him to look into reports that some of Vietnam's drug treatment centers "operate as forced labor camps."

This letter is based on reports from Human Rights Watch (HRW) that what Vietnam calls "labor therapy" is actually forced labor that is doing little to rehabilitate participants, an issue the Ros-Lehtinen letter also mentions.

"On the contrary, the relapse rate for released detainees is estimated at 80 to 97 percent," the letter said. "Yet HRW has found that the Vietnamese government persists in using it, often lengthening detention periods without due process while prison officials profit off of selling the cheap or free labor."

The letter said forced labor is a violation of international law. The lawmakers ask Shear to "keep attention focused on the allegations detailed in the HRW report" and "call publicly for the closure of these centers."