Western analysts are still poring over the evidence from North Korea's recent nuclear test – its third – for clues about what exactly the secretive Communist nation detonated Feb. 12.

Pyongyang claimed that its scientists had successfully miniaturized a nuclear device; if they are telling the truth, North Korea could be within a couple of years of the point of no return – the capability to fire a nuclear-armed missile at the west coast of the United States.

Twenty years of international efforts to deter North Korea from pursuing its dream of possessing nuclear weapons have proved fruitless. And it seems that the country best placed to put pressure on the North Korean government – its only ally, China – is unwilling to do so.

A new government takes over in Beijing this week, but analysts here do not expect the new president, Xi Jinping, to differ significantly from his predecessor when it comes to relations with North Korea – despite recent reports that China has agreed to support a new round of United Nations sanctions against the North. (Read this related article about Why China only expressed 'regret' following the North's recent rocket launch)

"There might be a change in our leaders' words and their tone, sending a more serious message to North Korea," predicts Sun Zhe, a professor at Tsinghua University's Institute of Modern International Relations in Beijing. "But I don't think that the fundamentals will change."

China is the driving force behind the Six Party Talks, intermittent negotiations over the past 10 years aimed at denuclearizing the Korean Peninsula and normalizing Pyongyang's relations with Washington and the rest of the world. But they made little headway, and North Korea pulled out of the talks in 2009.

At the same time Pyongyang expelled inspectors from the International Atomic Energy Agency who had been monitoring North Korea's promised actions to dismantle its nuclear reactor.

China has gone along with United Nations resolutions imposing economic sanctions on North Korea following its nuclear and missile tests. But Beijing has stopped short of halting the food, oil, and other supplies that keep its troublesome ally afloat.

China's calculation, say Chinese scholars, is simple: Making real sanctions bite would threaten the North Korean regime's stability, and what might happen then? An imploding North Korea could mean hundreds of thousands of refugees flooding across the border into China, and possibly a reunification of the peninsula under South Korean rule. That would mean US troops on China's border.

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A nuclear-armed but stable North Korea could be the least bad option for Beijing.

From that perspective, says John Swenson-Wright, an expert on Northeast Asian security issues at the Chatham House think tank in London, "I would be very surprised if we saw a sharp move by China to impose pain on North Korea."