President Barack Obama is condemning North Korea's latest nuclear test and says the U.S. "does not and never will" accept the country as a nuclear state.

Obama says he consulted by telephone with the leaders of South Korea and Japan after being informed of North Korea's claim to have conducted a "higher level" nuclear test explosion on Friday.

Obama says the leaders agreed to work with the U.N. Security Council and the international community to implement existing punitive measures imposed on North Korea for prior instances of unlawful nuclear activity. He says additional "significant" steps, including new sanctions, are being considered.

North Korea said its test will allow it to finally build, "at will," stronger, smaller and lighter nuclear weapons.

It was the country's fifth atomic test and second in eight months.