North Korea blows up its biggest-ever nuke: Kim Jong Un taunts Obama by detonating his second atom bomb this year - just hours after the President leaves Asia

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North Korea carried out its second nuclear test this year just hours after President Obama wrapped up his tour of Asia.

Pyongyang confirmed it conducted a successful explosion which triggered a 5.3-magnitude 'artificial' earthquake in the country's north east.  

The reclusive country boasted about its growing nuclear arsenal on state-controlled TV and said the test was in response to the strict international sanctions imposed against it. 

North Korea said it would continue to strengthen 'the quantity and quality' of its nuclear weapons.

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North Korea has carried out its second nuclear test this year (pictured, North Korean leader Kim Jong Un this week)

The explosion triggered a 5.3-magnitude 'artificial' earthquake in the country's north east (pictured, North Koreans watch a news report of a hydrogen bomb test in January)

It came just one day after Obama, speaking in the Vietnamese city of Laos, said he will strive to reduce North Korea's nuclear threat in his final months as president.

Obama called for a further tightening of sanctions against Kim Jong Un after the dictatorial leader fired three long range ballistic missiles this week.

'We are deeply disturbed by what's happened,' he said before calling on the country's sole ally China to work with the US to eliminate the threat it poses.

Obama spoke to the leaders of Japan and South Korea and promised to ensure that 'provocative actions from North Korea are met with serious consequences', a spokesman said.

South Korean President Park Geun-hye said the test as a clear violation of security council resolutions and accused Kim of 'maniacal recklessness'.

North Korea's state TV said the test 'examined and confirmed' features of a nuclear warhead designed to be mounted on ballistic missiles. 

Obama called for a further tightening of sanctions against Kim Jong Un on his tour of Asia

Speaking in the Vietnamese city of Laos (pictured), Obama said he will strive to reduce North Korea's nuclear threat

The reclusive country boasted about its growing nuclear arsenal on state-controlled TV (pictured)

It claimed there was no radioactive leakage or adverse environmental impact caused by the test.

The quake sparked by the nuclear bomb was between 5.0 and 5.3 on the Richter scale by various agencies.

The Yonhap news agency claimed that equated to a 10 kilotonne explosion - the country's biggest to date. 

Hiroshima's 15 kilotonne blast obliterated five square miles of the city and killed around 100,000 people.

US, European and Chinese agencies all picked up the tremor at 12:30am GMT, at surface level.

The quake sparked by the nuclear bomb was between 5.0 and 5.3 on the Richter scale by various agencies, including the Korea Meteorological Administration in Seoul (pictured)

The Yonhap news agency claimed the quake equated to a 10 kilotonne explosion

Test site: The quake was detected originating at Punggye-ri, the same place where North Korea's four confirmed nuclear bomb tests have occurred

The earthquake was detected near the country's only nuclear testing site, Punggye-ri, which has hosted all four of the country's confirmed nuclear tests so far. 

South Korea's Defense Ministry said Friday it could not immediately confirm the cause; the country's weather agency said it was analyzing the data.

But the US Geological Service and the China Earthquake Networks Center both reported a suspected 'explosion' in the area.

And Japan's Chief Cabinet Secretary Yoshihide Suga said at a briefing in Tokyo: 'We believe it's possible that North Korea carried out a nuclear test.

'The meteorological agency detected seismic waves that are probably not from a natural earthquake.' 

Celebration: North Koreans celebrate after hearing news of January's test. The country aims to build a nuclear missile that can reach the USA - though it's under an international ban

The quake comes ahead of Friday's National Day, which celebrates the founding of North Korea - a period in which the country usually flexes its military muscles.  

And there had been increased talk of a nuclear test after the US blacklisted Kim on July 6 for human rights abuses. 

In January this year, Kim Jong Un claimed to have detonated a hydrogen bomb - which can be hundreds of times more powerful than nuclear devices - at Punggye-ri.

But the resulting 5.1-magnitude quake was too small to have come from such a device, Lee Cheol Woo of South Korea's intelligence committee said at the time.

Activity: The Punggye-ri site (pictured) has seen increased activity in recent months, experts on the country say

That would suggest that whatever the origin of today's earthquake was, it wasn't a hydrogen bomb.

North Korea is under an international ban on developing and testing nuclear and missile technology - but has flouted that ban several times in the past few years.

The country aims to develop a nuclear-armed missile that could reach the US mainland.