Western and Asian powers will begin pressing this week for North Korea to be held liable for crimes against humanity documented in a United Nations report, but concede that their chances of influencing the isolated country are slim.

North Korean security chiefs and possibly even Supreme Leader Kim Jong Un should face international justice for ordering systematic torture, starvation and killings comparable with Nazi-era atrocities, U.N. investigators said last month.

Their findings, based on testimony from hundreds of victims, defectors and witnesses, were unequivocal. They demanded closure of political prison camps believed to hold up to 120,000 people and action by the International Criminal Court (ICC).

Michael Kirby, a former Australian judge who led the independent inquiry, officially presented the report to the U.N. Human Rights Council in Geneva on Monday. The forum, which commissioned the unprecedented investigation a year ago, will decide on how to handle North Korea at a session lasting until March 28.

Campaigners want action. “The fact that these violations are now deemed to be crimes against humanity triggers the responsibility of the international community to respond,” said Julie de Rivero of Human Rights Watch. “It might be a long route but steps need to be taken.”

Roseann Rife of Amnesty International said in a statement: “This is the first real test of the international community to show it is serious about acting on the Commission of Inquiry’s chilling findings. There needs to a concerted effort to ratchet up the pressure on the North Korean government to address these systematic, widespread and grave human rights violations.”

The country is already on the agenda of the U.N. General Assembly, but the Security Council has so far focused only on its nuclear weapons and proliferation threat, de Rivero said. “We are advocating that the Security Council needs to deal with crimes in North Korea.”

But winning international consensus to bring Kim to account will probably remain elusive for now, according to diplomats, U.N. sources and activists. This is particularly because Pyongyang’s ally China has veto powers at the Security Council, which would have to refer crimes in North Korea to the ICC.

China came under fire in the report for forcing North Korean refugees to return home, where they face possible persecution.

Beijing denies the charge, saying it favors “constructive dialogue” and has a long-standing position against what it regards as interference in the internal affairs of sovereign nations.

Pyongyang has rejected the report’s findings and the mandate of the investigators, whom it refused to meet or allow into North Korea, whose official name if the Democratic People’s Republic of Korea (DPRK). The team held public hearings in Seoul, Tokyo, London and Washington.

“The commission of inquiry on the DPRK is none other than a marionette representing the ill-minded purpose of its string pullers including the United States and its followers who are endeavoring to eliminate the socialist system on the pretext of human rights,” North Korea’s Ambassador So Se Pyong told the U.N. rights forum this month.

Ahn Myong Chul, a former North Korean guard at four prison camps, is a defector who testified and wants to see Kim and his loyal elite held accountable for gross abuses that began under the leader’s father, Kim Jong Il, and grandfather, Kim Il Sung.

“Over 60 years North Koreans have suffered severe oppression under three generations of the regime. These are basic human rights, their voices should be heard. The government must be punished,” Ahn said.

Inquiry leader Kirby said it is time to act rather than talk. “What is unique has been the capacity of North Korea to avoid international scrutiny, to avoid examination of its record over such a long time, effectively 60 years of very great wrongs against its population,” he said.

“Now we have a full volume book that tells it all in a comprehensive manner. The moment of truth has approached. We must turn it into action,” he added.

Human rights were among the founding principles of the United Nations in the wake of World War II, after discovery of atrocities against Jews and minorities, he said. He wants North Korea referred to the ICC or to a special ad hoc tribunal.

China will have a pivotal say in the Security Council, dimming hopes for quick action. As Pyongyang has not signed the Rome statutes setting up the Hague-based ICC, its prosecutor can act only at the request of world powers.

Japan and the European Union led the effort a year ago at the Geneva rights council for the inquiry into persistent allegations of crimes against humanity in North Korea.

The U.S. has backed their drive to hold Pyongyang accountable and is being closely consulted on the next move, along with South Korea, diplomats say. But Washington has qualms about explicitly calling for a referral to the ICC, as it signed but never ratified the Rome treaty, they add.

The Japanese-EU resolution to set up the inquiry won unanimous approval at the 47-member forum partly because China, Cuba and Russia were not members at the time. The absence of the trio, which reject country-specific resolutions, was seen as a rare opportunity to investigate one of the most secretive countries in the world.

“We thought it was a once-in-a-lifetime opportunity,” said Kwon Eun-kyoung of the International Coalition to Stop Crimes Against Humanity in North Korea, an alliance of more than 40 groups, which lobbied governments to seize the chance.

North Korean defector Jee Hyeon-a is less hopeful about quick results this time. “It can only be possible to bring Kim Jong Un or his subordinates to the ICC after North Korea collapses,” said Jee, who was sent back by China three times and eventually fled to South Korea after being jailed in the Jeungsan re-education center, one of North Korea’s worst camps.

As the Human Rights Council discusses how to handle North Korea, the main actors are staking out their ground. The EU, in a speech delivered by Greek Deputy Foreign Minister Dimitris Kourkoulas two weeks ago, said the bloc wanted proper follow-up to ensure accountability.

EU and Japanese diplomats have held several rounds of confidential talks in Geneva to hammer out a resolution for consideration at the rights forum.

Their latest joint draft text, reviewed by Reuters, urges the General Assembly to submit the report to the Security Council for appropriate action, including “consideration of referral to the appropriate international criminal justice mechanism and targeted sanctions against those who appear to be most responsible for crimes against humanity.”

Japan is keen to maintain global consensus on North Korea even if the text has to be watered down to achieve a united front, but the EU is fighting for strong wording, diplomats say.

Because China, Cuba and Russia are back as members on the council, along with Venezuela and newcomer Vietnam, the likelihood of consensus in the rights forum is now close to zero, but the resolution should be adopted easily, diplomats say.

A “no” vote by China and Russia in Geneva would not augur well for any future steps at the Security Council, they add.

The EU-Japan proposal also lays out a parallel path: the creation of a small U.N. human rights office dedicated to documenting crimes and raising awareness. This would probably be based in Seoul or Bangkok, collecting more evidence and testimony to widen the database.