South Korea on Friday strongly condemned the DPRK's fifth nuclear test, calling it a "grave provocation that cannot be overlooked". 

"Although the international community once again has sent a strong, clear warning to North Korea through the G20 and ASEAN summits, North Korea explicitly violated the UN Security Council Resolutions and went ahead with its second nuclear test this year," said Cho Tae-Yong, National Security advisor.

"This is a grave provocation that cannot be overlooked, and the South Korean government strongly denounces this test."

Seoul considers tougher sanctions

Cho Tae-yong said his government once again is urging the DPRK to immediately nullify its nuclear and missile programs in a complete, provable and irreversible way. And South Korea will consider stronger sanctions in conjunction with the international community.