SEOUL, South Korea — North Korea conducted its fifth underground nuclear test on Friday, its government said, despite threats of more sanctions from the United States and the United Nations. The latest test, according to South Korean officials, produced a more powerful explosive yield than the North’s previous detonations, indicating that the country was making progress in its efforts to build a functional nuclear warhead.

The test confirmed the explosive power and other characteristics of a “nuclear warhead that has been standardized to be able to be mounted on” its ballistic missiles, the North’s nuclear weapons institute said in a statement on Friday.

A statement from the South Korean military also said that an artificial tremor, registered as magnitude 5, had originated from Punggye-ri in northeastern North Korea, where the North has conducted its four previous underground nuclear tests.

A senior official at the Defense Ministry later told reporters that it had concluded that a nuclear detonation had caused the tremor.