The White House says the U.S. government’s early analysis of underground activity in North Korea “is not consistent” with that country’s claim of having conducted a successful hydrogen bomb test.

Spokesman Josh Earnest also says nothing has happened to change the U.S. government’s assessment of North Korea’s technical or military capabilities.

He says the U.S. government is still doing the work that’s needed to learn more about the nuclear test North Korea claims to have conducted successfully on Wednesday.

Pyongyang’s announcement of a successful hydrogen bomb test would mark a major and unanticipated advance for its still-limited nuclear arsenal.