Military leaders changed the official name to "Myanmar" in 1989, saying that the old term "Burma" was a sorry legacy of British colonialism and implied that the ethnically torn land belonged only to the Burman majority.
But the opposition and exiles fiercely opposed the change, seeing it as a symbolic step to create an entirely new country, and the United States has stood in solidarity by calling the nation Burma.
On Friday, however, Secretary of State John Kerry twice referred to "Myanmar" in a statement marking the country's independence day. The statement made no mention of "Burma."
Deputy State Department spokeswoman Marie Harf told reporters Monday that "it continues to be US government policy to refer to the country as Burma."
But "in certain settings, US government officials refer to the country as Myanmar as a diplomatic courtesy," she added, citing President Barack Obama's visit to the country in 2012 when he alternated between the two.
"I don't think there's a confusion," she said.
In October, Kerry said the longtime pariah state's dramatic political reforms were "exciting" but still "incomplete."
As part of its reconciliation with Myanmar, which included Obama's visit, the United States has increased development aid and ended most economic sanctions on the resource-rich and strategically placed country.