U.S. , South Korea and Japan talk of ` ` significant consequences '' after a bomb test . U.S. officials told CNN last week that the North appeared to be ready test another nuclear device `` at any time . '' U.S. officials say a new North Korean nuclear test could come at any time . South Korea 's president tells his government to be cautious .
U.S. , South Korea and Japan talk of ` ` significant consequences '' after a bomb test . U.S. officials say a new North Korean nuclear test could come at any time . South Korea 's president tells his government to be cautious .