As North Korea edges closer to becoming a true nuclear power, it falls upon China to join the rest of the world in taking a definitive stand.

China, with much to lose if war starts in that part of the world, must act assertively to prevent its neighbor from becoming a nuclear threat.

North Korea is an unstable country, seemingly immune to sanctions. Under new leader Kim Jong-un, it is also a country that does not seem to care whether a percentage of its population starves as it pursues its nuclear ambitions.

The reaction to North Korea’s third nuclear test was immediate. President Obama called it a “highly provocative act” demanding “swift and credible action by the international community.” There was condemnation by Russia, Britain, South Korea and the United Nations.

North Korea ignored previous warnings about its nuclear and ballistic missile programs and will ignore the latest response unless China participates fully in economic sanctions.

China is North Korea’s closest ally and has been reluctant to impose tough sanctions on its neighbor. As the Council on Foreign Relations recently noted, among its neighbors China has shown the greatest policy variability in response to the nuclear tests.

China’s statements have included harsh criticism following a 2006 test and support later for a stronger-than-expected U.N. Security Council resolution condemning the tests. Then China turned around and launched a comprehensive engagement policy toward North Korea that included protection of the North from international condemnation.

Last month, China decided to support a U.N. Security Council resolution criticizing North Korea’s December satellite launch.

Several hours after this latest nuclear test, China exhibited its indecisiveness once again by expressing “staunch opposition” to the test but calling for “all parties concerned to respond calmly.”

Obama is expected to use his State of the Union address to call for drastically reducing nuclear arms around the world. In addition to that public track, Obama also needs to demonstrate to the Chinese that it is in their best interest not to have an unstable, nuclear-armed nation on their border.