North Korea has conducted its most powerful nuclear test to date, sending tremors as far as South Korea and China and drawing condemnation worldwide.
A magnitude-6.3 earthquake was detected near a nuclear test site in north-east North Korea yesterday around 12.30pm local time (11.30am Singapore time), before its state media announced hours later that it had successfully tested a missile-ready hydrogen bomb.
In a TV broadcast, Pyongyang residents raised their arms in triumph as a television newsreader lauded the "unprecedentedly large" blast.
The North Korean report said the bomb had an explosive power adjustable up to hundreds of kilotons. It said the weapon can be detonated even at high altitudes to launch an electromagnetic pulse attack, which can destroy electronic devices in a vast area.
The nuclear test - the North's sixth since 2006 and its first since United States President Donald Trump took office - was swiftly condemned. Mr Trump called North Korea a "rogue nation" in a tweet.
China's Foreign Ministry strongly condemned the test, which came as China - North Korea's main ally - was hosting the annual Brics Summit involving Brazil, Russia, India, China and South Africa.
Chinese President Xi Jinping and Russian President Vladimir Putin, who met on the event's sidelines, agreed to "appropriately deal with" the latest nuclear test, Chinese state news agency Xinhua said.
South Korea, Germany and France all called for stronger sanctions. Calling the test an "absurd strategic mistake", South Korean President Moon Jae In proposed "all diplomatic measures" and talks to deploy the "strongest strategic assets of the US military".
Japan's Prime Minister Shinzo Abe slammed the "absolutely unacceptable" provocation, saying the North's nuclear programme has entered a new stage. Singapore's Foreign Ministry condemned the test as a "blatant disregard of the grave concerns of the international community".
The provocation came five days after North Korea launched a missile that flew over Japan.
The Korea Meteorological Administration said the scale of yesterday's artificial quake was five to six times that of the fifth test in September last year, which had a yield of 10 kilotons and sparked a 5.04-magnitude earthquake. In South Korea, 31 reports of tremors were filed nationwide, with 13 in Seoul alone.
Analysts said the nuclear test was no surprise, as North Korea has been accelerating its missile and nuclear programme.
Dr Bong Young Shik of Yonsei University's Institute for North Korean Studies said the test has made it tougher for the US to decide how to deal with North Korea. "Not conducting nuclear tests is a pre-condition (to dialogue), and North Korea has violated it. Will you continue to back negotiations with North Korea? You need to, but how are you going to save your face?"