"We have been in close consultation with countries such as the USA and Japan on our government's basic stance on humanitarian aid and other overall policies related to the North", Cho June-hyuck, foreign ministry spokesman, told a regular press briefing.
Following Monday's UN Security Council vote in support of the US-drafted sanctions resolution aimed at forcing the North Korean supreme leader Kim Jong-un to abandon the nuclear weapon and missile programmes, Pyongyang vowed to redouble its efforts to acquire weapons of mass destruction and warned that the United States would face "the greatest pain it ever experienced in history" for leading a push for harsher UN sanctions.
North Korea's tests have inched the country closer to producing nuclear-tipped weapons that could one day reach the American mainland.
Xenon is a naturally occurring, colorless gas that is used in manufacturing of some sorts of lights.
"If the claim that the device just tested has a variable yield is true (from tens to hundreds of kilotons), then this may also imply the North Koreans intend to adopt an expanded policy of using nuclear weapons, including tactical use, in addition to deterring threats to existence of the state", 38 North said.
Beijing and Moscow say that sanctions should be followed with diplomatic solutions.
There is evidence the North Koreans will not stop tests at Punggye-ri, they said. The analysts gave no indication that a test appeared to be imminent.
Pyongyang claims it detonated a hydrogen bomb in this latest test, which its state media swiftly described as "a flawless success".
The Korea Asia-Pacific peace committee, which oversees North Korea's relations with the outside world, described the UN Security Council, which passed a new round of sanctions earlier this week, as a "tool of evil" in the pay of Washington, and called for it to be broken up, the Guardian newspaper reported on Thursday.
On Thursday, North Korea issued another threat, this time targeting both Japan and the US.
On the other hand, Mattis has called the submarine-based component "sacrosanct" and also has said it is necessary to retain the ability to fire nuclear weapons from planes.
"This is in order to make the right conditions for dialogues and I would like to emphasize this", he said. Five days later, it carried out a sixth nuclear test, sending tensions soaring over its weapons ambitions and causing global concern.
A pre-emptive strike against Pyongyang's leadership is widely seen as the most realistic of the limited military options Seoul has to deny a nuclear attack from its rival.
A Taurus "bunker buster" cruise missile released from a South Korean F-15 fighter "ies to its target Wednesday in what officials said was a successful".