Lips and Teeth - By Shen Dingli

SHANGHAI ' Over the last two months, Beijing has conveyed its concerns to North Korea about conducting a nuclear test. Yet on Feb. 12, China's neighbor detonated its third nuclear weapon -- smaller and more powerful than the two that preceded it. Foreign Minister Yang Jiechi said China was "strongly dissatisfied and resolutely opposed" to the test, but, as with North Korea's bad behavior in the past, will likely not follow with tougher action.

China likely handles North Korea with kid gloves because it fears what would happen if the regime collapsed. If things turned bad, tens if not hundreds of thousands of refugees could flee across the border, destabilizing parts of northeastern China. North Korea's eventual reunification with South Korea might lead to a democratic U.S. ally with the potential for tens of thousands of U.S. and Korean troops stationed along China's border. And the millions of Korean-Chinese living in the border regions are one of China's most stable ethnic minorities; unlike the Tibetans and Uyghurs, they have not called for independence. If the Korean Peninsula were unified, this could change. This is part of the reason why China provides North Korea with presumably large amounts of aid as well as diplomatic cover at the United Nations.

And what thanks does China get in return? Lies, insults, and provocations. On Jan. 22, after the U.N. Security Council unanimously passed Resolution 2087 as a response to Pyongyang's December "satellite" launch, North Korea responded by announcing that the six-party talks over its nuclear program have ceased to exist. Since 2003, China has worked hard to bring North Korea to those talks, asking for it to commit to nuclear abandonment while assuring it with development and security aid. China tried to water down the sanctions; instead of being grateful, Pyongyang hinted that some major powers had been manipulated by the United States.

North Korea's threatening behavior, meanwhile, has made the region less stable. By firing artillery at South Korea's Yeonpyeong Island in 2010, killing four people, North Korea has pushed the envelope too far, undermining China's interests in keeping Northeast Asia stable. And now, this third nuclear test not only discredits Chinese diplomacy, but also provides a ready excuse for the United States to expand its military presence in the region. In his State of the Union address Tuesday, U.S. President Barack Obama vowed to boost America's missile-defense efforts in Asia -- U.S. technology that China doesn't welcome.

Let's face it: China has reached a point where it needs to cut its losses and cut North Korea loose.