The US embassy in Bangkok said Thursday it was running newspaper advertisements in Thailand and Laos to revive an investigation into the year-old disappearance of two Hmong-Americans.
One of the men, Michael Vang, is the nephew of General Vang Pao, the former leader of the Hmong insurgents who fought against the communists in Vietnam and Laos during the Indochina War of the 1960s and 70s.
"We have placed a couple of advertisements in Thai and Lao newspapers related to the disappearance of these two indviduals," a spokeswoman for the embassy said.
To date, she said, "we don't have a lot of information".
"The purpose is to try to cast a wider field because people have not been entirely aware of the disappearance ... it's one more attempt to reach out to people."
The reclusive government in Vientiane has said it knows nothing about the fate of the two men who went missing after reportedly being seen along the northern Thai-Laos border.
But Laos has claimed Hmong-Americans are funding arms smuggling operations across the porous border, to equip the Hmong insurgents who have battled the government intermittently since the 1975 communist takeover.
General Vang Pao is still prominent among the Hmong resistance community in the United States and has been accused by Laotian officials of plotting this year's recent series of bombings in the country.
The general has angrily denied the accusations, and diplomats in Vientiane agree the Hmong are unlikely to be behind the bombings.