North Korea nuclear program
North Korea nuclear program iStock

South Korea, Japan and the United States agreed to stern measures against a new nuclear test by North Korea, South Korea's top security adviser said Thursday, according to the Yonhap news agency.

The adviser, Kim Sung-han, made the remarks after a trilateral meeting with his US and Japanese counterparts -- Jake Sullivan and Akiba Takeo Akiba -- in Honolulu.

"(We) agreed that there must not be naive thinking or reaction that North Korea has conducted six nuclear tests and that (a new test) will only be one more nuclear test," Kim was quoted as having told reporters before heading home.

"Should North Korea conduct its seventh nuclear test, our reaction will certainly be different from those until now," he added.

North Korea conducted its sixth and last nuclear test in September 2019, but officials in Seoul and Washington have warned that it appears to have completed "all preparations" for another nuclear test and that it may only be gauging the timing.

North Korea has conducted more than a dozen weapons tests since January, including the firing of an intercontinental ballistic missile at full range for the first time since 2017.

In May, it fired a volley of missiles, including possibly its largest intercontinental ballistic missile.

In July, Pyongyang fired what appeared to be multiple rocket launchers.

The United States and South Korea have warned of a “swift response” if North Korea conducts a nuclear test, but have also offered talks as a way out.

North Korean leader Kim Jong Un, for his part, has said his country is ready to mobilize its nuclear war deterrent and for any military clash with the United States.