MOSCOW (Sputnik) – Earlier in the day, an earthquake occurred in South Korea, prompting Seoul's suspicions that Pyongyang had performed a nuclear test. North Korea subsequently confirmed that it had successfully tested a hydrogen bomb.
"We will be working with other UN Security Council members to ensure the international community responds urgently and decisively to this latest activity," Philip Hammond said in a statement.
The move is a "grave breach" of the UNSC resolutions, deserving condemnation, Hammond stressed.
"I have discussed this matter today in Beijing with my Chinese counterpart, State Councillor Yang Jiechi, and we have agreed to work with other members of the UN Security Council towards a robust international response," he added.
North Korea declared itself a nuclear power in 2005 and conducted a series of underground nuclear weapon tests in 2006, 2009 and 2013.