The terrifying tremor was detected in the northeast of the country where the Punggye-ri test site is located - but was so strong that it shook buildings in China and Russia.
State television claimed the country's sixth nuclear test - 10 times more powerful than its fifth - was a "perfect success" on September 3 and could pave the way for a frightening new range of missiles loaded with hydrogen bombs.
It added that the underground test - which was directly ordered by leader Kim Jong-un - was a 'meaningful' step in completing the country's nuclear weapons programme.
Foreign Secretary Boris Johnson condemned the "reckless" nuclear weapon test and stressed that 'all options are on the table' when pressed on military action.
But he warned: "The distance between North Korea and Seoul is very very small - they could basically vaporise large parts of the South Korean population even with conventional weapons."
Following the blast US president Donald Trump slammed North Korea as a "rogue nation" which is a "great threat and embarrassment to China" - finishing with the thinly-veiled threat: "They only understand one thing."
He wrote on Twitter: "North Korea has conducted a major Nuclear Test. Their words and actions continue to be very hostile and dangerous to the United States.
"North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success.
"South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!"
It comes after news today that the United Arab Emirates will stop issuing new visas to North Korean workers, becoming the latest Gulf country to limit Pyongyang's ability to evade sanctions and raise money abroad amid tensions with the US.
A statement by the UAE Foreign Ministry did not address the hundreds of North Korean laborers already working in the Emirates. A call to the UAE's Embassy in Washington was not immediately returned.
The statement said the UAE would pull its non-resident ambassador to North Korea as well as stop North Koreans from opening new businesses in the Emirates, a federation of seven sheikhdoms on the Arabian Peninsula that is a staunch U.S. ally.
The UAE "looks forward to a unified global front against North Korea's nuclear weapons and missile program," the statement read.
It's not clear what prompted the decision, though American officials have been pressuring their allies in the Gulf Arab states to cut back on economic ties to North Korea. The US Embassy in Abu Dhabi did not immediately respond to a request for comment.
Last month, Kuwait announced it would expel North Korea's ambassador to the oil-rich country and four other diplomats, as well as limit visas. North Korea's Embassy in Kuwait City serves as its only diplomatic outpost in the Gulf. Qatar has said 'less than 1,000' North Koreans are in the country and their visas will not be renewed. North Korean laborers also are in Oman.
The US and Asian nations have increased pressure on their allies to cut ties as Pyongyang has tested a nuclear weapon and launched ballistic missiles over Japan.
