A senior United States official on Tuesday disclosed further details about a covert nuclear-related test allegedly carried out by China while stressing the U.S. cannot afford not to resume testing to some degree, to avert an "intolerable disadvantage" in an era of two nuclear peer rivals. China , like the U.S. and Russia , signed the 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT), which prohibits nuclear weapons test explosions in any environment, including space. While none of the three has