As North Korea's biggest political ally and benefactor, China would appear to hold all the cards when it comes to reining in Kim Jong Un's regime.
However, its response to Pyongyang's latest nuclear test was rather muted Tuesday.
Beijing's foreign minister summoned North Korea's ambassador for a dressing down and sternly expressed "strong dissatisfaction and firm opposition" to the test.
As a permanent member of the UN Security Council, Beijing will also join in a meeting set for later this week to discuss how best to respond to the nuclear test. But it remains unclear if Beijing will support tougher new sanctions, or that any new round of UN sanctions or resolutions will have much impact on the reclusive nation's actions.
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Since the 1950-1953 Korean War, North Korea has been subjected to an array of multinational and unilateral sanctions by the international community. The country's leaders have responded to the isolation by focusing even more intently on developing sophisticated weapons and rocket programs that have simultaneously infuriated regional neighbors and drawn them to the negotiating table.
Many regional observers have suggested that international sanctions are doomed to failure as long as Beijing continues to prop up and sustain its neighbor through aid and investment.
Indeed, over the years China has staunchly supported North Korea on the international field, arguing that individual countries have the right to develop rocket programs that were scientific in nature and helping to derail stiffer sanctions against North Korea by the UN.
Last month's surprise announcement that China had joined in with the rest of the UN Security Council in condemning North Korea's latest rocket test seemed to represent a shift in its way of engaging with its neighbor, and long-time Communist comrade. However, it later emerged that China had worked hard to block any new sanctions.
(Read More: North Korea Snubs Key Ally China With Rocket Test)
The Associated Press noted: "Despite being the North's biggest source of aid and diplomatic support, Beijing has been reluctant to back more severe measures that could destabilize the North's hardline regime, which serves as a buffer between China and democratic South Korea backed by U.S. forces."
In the weeks leading up to Tuesday's nuclear test, it has been widely reported that China had been working behind the scenes with North Korea to halt the test and suspend their nuclear program.
Officially, China's Foreign Ministry has maintained steady support for North Korea by lamely calling for peace on the Korean peninsula and greater engagement by all parties.
But in China's state-run media, the frustration towards North Korea has become obvious.
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A strongly worded opinion piece last week in the typically nationalistic Chinese newspaper, Global Times, called on China's ruling Communist Party to take a tougher stance on North Korea provocations.
"If North Korea insists on a third nuclear test despite attempts to dissuade it, it must pay a heavy price," the paper said, effectively calling for an end to Chinese economic aid to the struggling country as punishment.
The Global Times certainly does not reflect official Chinese policy; state censors tend to give greater latitude to papers like the Global Times, using such media as a spigot from which to turn nationalist sentiment on and off while also gauging popular opinion. But it could indicate the direction China may be prepared to go to ensure stability on its borders.
Although tougher economic sanctions backed by China might cause Kim and his generals to reconsider their drive for more sophisticated nuclear devices, the move could also alienate Pyongyang and create a nuclear-armed rival on its doorstep.
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It is for this reason — and the fact that China's leadership transition is not yet complete, with Xi Jinping still not formally president until June —that Beijing's reaction to North Korea transgressions will likely remain subdued.
It appears likely that China will join the Security Council this week in condemning the North Koreans for this nuclear test, but it remains unclear which way Beijing will fall on stronger sanctions.
Their decision could finally shed some light on the opaque political calculus that Beijing uses in dealing with its wayward old ally North Korea.