North Korea is repeating a tedious cycle of a provocation triggering international sanctions. The same pattern has repeated itself ever since North Korea announced its withdrawal from the nuclear non-proliferation treaty 20 years ago.

So why does it continue? The answer is that the international community has stubbornly refrained from hitting North Korea where it really hurts.

Pyongyang has staged several publicity stunts to sway international opinion, such as announcing it would freeze its nuclear facilities and blasting a cooling tower at a reactor. But it never wavered from its nuclear ambitions. Now, after the third nuclear test, the international community has rallied around Washington to look for new sanctions. But they will be ineffective unless China gets fully behind them.

In fact, North Korea has already threatened to launch further provocations if the international community imposes further sanctions. The only way to prevent more aggression is to hit the regime where it hurts.

North Korea would be hit hardest if its oil supply dried up, followed by stopping food aid and financial sanctions. Halting the supply of oil and food to North Korea would yield immediate effects. In both areas China holds the key.

Around 10 years ago, China shut down a pipeline that funneled oil to North Korea. Financial sanctions also have mid- to long-term effects on North Korea. In 2006, the U.S. froze a bank account at Macao’s Banco Delta Asia believed to belong to then North Korean leader Kim Jong-il which contained millions of U.S. dollars. That really hurt Pyongyang, because North Korean officials placed the lifting of that sanction on the top of its agenda in ensuing talks with the U.S.

The North Korean regime has hundreds of secret bank accounts in Chinese banks. Freezing them would deal a much harder blow than the freezing of the Banco Delta Asia account. But the U.S. needs China's cooperation.

China apparently has no plans at the moment to shut off oil and rice aid to North Korea. But it should start thinking about it. If North Korea fully arms itself with nuclear bombs, South Korea and Japan would be the only countries in Northeast Asia that lack such weapons. How much longer would Japan be willing to refrain from acquiring its own nuclear weapons as it continues to clash with China over the Senkaku or Diaoyu Islands?

And if Japan decides to acquire nuclear weapons, then South Korea would have to follow suit. That would lead to a spiraling nuclear arms race in Northeast Asia.

The U.S. may be most concerned about that scenario, but China would not be safe either from the impact of nuclear proliferation. Beijing needs to decide whether it would serve its national interests to leave North Korea alone and trigger a larger threat, or to join the international community in tackling Pyongyang's provocations, even if that would temporarily damage ties with its renegade ally, so the North can finally be persuaded to abandon its nuclear ambitions.