Top U.S. nuclear official confirms plans to restart American nuclear testing, citing a need to match covert tests by Beijing and Moscow.

The United States accused Beijing on Friday of conducting a secret nuclear test in 2020 as it called for a new, broader arms control treaty that would bring in China as well as Russia.

Arms control advocates warn that the expiration of the treaty will fuel an accelerated nuclear arms race, while U.S. opponents say the pact constrained the U.S. ability to deploy enough weapons to det...