North Korea's surprise claim that it had successfully conducted a fourth nuclear bomb test this week renewed fears and ignited a chorus of condemnation around the world.

If confirmed, the detonation would be the first to use fusion technology - a major step up in North Korea's nuclear weapons capability.

South Korea and Japan had swiftly threatened increased sanctions, and pledged with the US to forge a "united and strong" international response. The United Nations Security Council also agreed to draw up new measures against North Korea. 

The isolated communist regime's most important economic ally, however, has so far only called on Pyongyang to return to the negotiating table and to give up its nuclear weapons. 

On Wednesday, China's foreign ministry released a statement saying it "firmly opposes" the test, and a spokeswoman told reporters that Beijing would be summoning Pyongyang's ambassador to lodge a complaint. 

This is not the first time China has disappointed international leaders with a weak response to its neighbour's hydrogen bomb testing.

Pyongyang tested its first nuclear device 10 years ago, contravening Security Countil resolutions and leading to the imposition of economic sanctions by the UN.

China did not use its veto power on the UN Security Council to block such sanctions, but its government has also not answered calls to leverage its power to put stronger pressure on North Korea. 

In 2013, Beijing cut crude oil exports to North Korea following the country's previous nuclear test but stopped short of cutting ties that would have seriously affected the country's economy.

"There is no doubt that China is a kind of lifeline for North Korea," said Eric Ballbach, an expert on North Korea at Berlin's Freie Universität. "But China has not been willing to use this economic influence with full force and this has not changed even after the most recent test."

China's foreign ministry confirmed Wednesday it had not received advanced warning that North Korea would be conducting the nuclear test.

While this was a "clear snub" to the Chinese leadership, Beijing may still only pursue "subtle coercive measures" such as the temporary restriction of economic cooperation pilot projects, said Mikko Huotari of the Mercator Institute for China Studies.   

"China's strategy continues to be characterized by the following priorities: No war, no instability, no nuclear weapons," Huotari said.  

China is treading carefully because it is afraid the Kim Jong-un leadership will collapse if there is too much pressure on the regime's economy. This could potentially lead to a flood of North Korean refugees into China, experts said. 

"The worry is always there for China. They will not cut military support and investment in North Korea even if they are willing to make some economic sanctions," said Yu Yingli, associate researcher at the Shanghai Institutes for International Studies. 

International observers could also be overestimating China's friendship with North Korea. 

China's president Xi Jinping and Kim Jong-un have never met and Chinese state media have increasingly published scathing criticism of the regime. 

"China has cleaned up the DPRK's [Democratic People's Republic of Korea's] mess too many times... But it doesn't have to do that in the future," retired Chinese general Wang Hongguang wrote in the state-run Global Times in 2014. 

Wang's commentary also accused North Korea of violating the spirit of the two countries' mutual defense treaty by failing to consult China on its nuclear programme. 

However, following a long frosty period between the countries, the Chinese leadership sent a politburo member to a military parade in October to mark 70 years since the founding of the Workers' Party of North Korea, suggesting a thaw in relations.

"China and the international community have to work to find an effective strategy because North Korea is not listening to anyone," said Zhang Liangui, a professor at the the Institute for International Strategic Studies of the Central Party School of the Communist Party of China. 

"Pushing for sanctions is still important. If there were no sanctions at all, North Korea's nuclear weapon's development would be even faster. Sanctions might not eliminate the threat, but it may help to slow their weapons development," said Shi Yinhong, international relations professor at the People's University in Beijing. 

Latest news

Syrian opposition rules out future role for President al-Assad

The Syrian opposition said Friday it would not accept any role for President Bashar al-Assad in the future of the war-torn country, reacting to a recent US shift saying that removing al-Assad is no longer a priority for Washington.

Russian Army integrates breakaway forces of Georgian province

Parts of the small fighting forces of the Georgian breakaway province of South Ossetia have been placed under Russian military control, Russian Defence Minister Sergei Shoigu said on Friday.

Czech Republic's Pilsner Urquell beer is now Japanese

Japanese brewing company Asahi completed its takeover of the Czech brewery Pilsner Urquell on Friday, Asahi said in a statement.

Judge approves 25-million-dollar settlement of Trump University case

A US district judge on Friday approved a 25-million-dollar settlement of lawsuits and state fraud allegations against Trump University, the US president's now-defunct business venture.

Former Thai premier Thaksin to junta on reconciliation: 'Cut me out'

Former Thai prime minister Thaksin Shinawatra on Friday announced that he is not interested in the junta-led reconciliation process, three days after the junta handed him a half-a-billion-dollar tax bill for his past business deal.

Dalic: We welcome possible deal between Agrokor and banks

The government welcomes the possibility of an agreement being concluded between the Agrokor food company and creditor banks, and the bill on vitally important companies is not a fallback plan but the result of the government's care for the overall economic and financial stability of Croatia, Deputy Prime Minister and Minister of Economy Martina Dalic told a press conference in Zagreb on Friday.

Croatia, China sign action plan for cooperation in agriculture

The Croatian and Chinese ministries of agriculture on Friday signed an action plan for cooperation in the field of agriculture for the period 2017-2018, the Croatian ministry said in a statement.

ZSE indices up, Agrokor shares in focus of investor interest

The Zagreb Stock Exchange (ZSE) indices on Friday rose by more than 1.8%, with stocks of the Agrokor food and retail concern being in the focus of investor interest again.

Berlin police defend handling of Berlin market attacker

Berlin police defended themselves on Friday against accusations that they stopped surveillance on Berlin Christmas market attacker despite knowing in June 2016 he was dangerous.

Croatia, creditors tailor emergency measures to save tottering giant

Croatia's tottering retail and food giant Agrokor reached an agreement with its creditors, putting its debts standby and allowing it to continue working during emergency restructuring, the Croatian branch of Austria's Erste Bank said Friday.

Agrokor's creditors say standstill agreement to go into force today

A standstill agreement regarding the Agrokor concern's existing financial obligations to banks will take effect on Friday, additional capital will be injected into the concern in the coming days and the concern will be actively restructured, which includes a change of its management, it was said on Friday after a meeting between Agrokor's suppliers and creditor banks.

Palestinians, UN slam Israel's new settlement plan

Palestinians, Israeli activists and the UN lambasted the government of Israeli Prime Minister Benjamin Netanyahu on Friday, a day after it gave the go-ahead for the first new West Bank settlement in a quarter of a century.

South Sudan rebels release three abducted foreign oil workers

South Sudanese rebels have released three foreign engineers they abducted in early March in the oil-rich Upper Nile region, Foreign Affairs Ministry official Mawein Makol Arik said on Friday.

Turkish opposition: Imprisoned party chief has gone on hunger strike

The head of Turkey's pro-Kurdish opposition party has launched a hunger strike from prison.

European leagues threaten Champions League schedule clashes

The European Professional Football Leagues (EPFL) on Friday threatened schedule clashes on Champions League matchdays in an ongoing dispute with the governing body UEFA.

Danish court revokes citizenship of IS volunteer

A Danish appellate court on Friday stripped a man of his Danish citizenship for volunteering to fight for the extremist Islamic State in Syria.

Banks and Agrokor agree on key elements of standstill agreement

Member banks of the coordinating committee of financial creditors and representatives of the Agrokor food company have in principle agreed on key elements of a standstill agreement, which is expected to be signed later today, announcing changes in the company's management team, Erste Bank said in a statement on Friday afternoon.

Syrian man on trial in Sweden; mosque attack labelled terrorism

A Syrian man went on trial Friday in the southern Swedish city of Malmo, charged with terrorism and arson after an attack last year on a building used as an assembly hall by Shiite Muslims.