North Korea has again openly defied the international community, first by launching a rocket in December 2012 and then detonating a nuclear weapon. Pyongyang's eagerness to conduct a nuclear test so quickly after it was chastised by the United Nations shows the ineffectiveness of weak and toothless Security Council resolutions.

Pyongyang's actions also clearly show that Kim Jong Un is no less belligerent or dangerous than his predecessors. North Korea also demonstrated that it has no intention of abandoning its nuclear arsenal, particularly when it faces no real penalties from the international community.

The regime proclaimed it refuses to participate in any denuclearization negotiations and that its future missile and nuclear tests will "target the United States." It is evident that North Korea did not devote decades of efforts and countless billions of dollars merely to create a bargaining chip to give away.

The United States was complacent after the U.N. passed Resolution 2087, passively waiting for Pyongyang's nuclear test, hoping to better persuade China for firmer measures. Such an approach is deeply flawed, since it does little to pressure North Korea, and cedes initiative to China, which has resisted bringing any pressure on Pyongyang.

China also undermines any incentive for Pyongyang to return to the Six Party Talks by engaging economically with North Korea. Rather than facing the conditionality of the nuclear negotiations, the belligerent regime can get what it needs from China through direct assistance and bilateral trade.

Despite the steadily growing North Korean threat, the Obama Administration remains reluctant to implement more expansive and effective sanctions. This policy timidity emboldens Pyongyang to continue expanding and improving its nuclear weapons and missile delivery arsenal. A more robust sanctions regime would increase the cost to Pyongyang for its defiance.

Since the U.N. has been reluctant to impose measures, the United States should unilaterally publicly identify all North Korean and foreign banks, businesses and government agencies suspected of violating U.N. resolutions. Washington should freeze and seize the financial assets of any entity violating U.N. resolutions and international law.

The Obama Administration should then call upon other nations to reciprocate U.S. actions against North Korean and foreign violators. It should also lead an international effort against North Korean illegal activities, including currency counterfeiting and drug smuggling. U.S. law enforcement actions in 2005 against Pyongyang's accounts in Banco Delta Asia were highly effective, but were later abandoned in acquiescence to North Korean demands to "improve the atmosphere" for nuclear negotiations.

Such punitive measures, implemented in tandem with continued offers of conditional engagement, are more likely to alter North Korea's cost/benefit calculations than timorous measures imposed to date.

The U.S. must make clear to North Korea that its provocative actions will doom inter-Korean reconciliation offered by incoming South Korean President Park Geun Hye and lead to further allied military measures. Washington should also stress to the new Chinese leadership that continued sheltering of its recalcitrant ally only increases the potential for a crisis on the Korean Peninsula.

-Bruce Klingner is a senior research fellow for Northeast Asia at the Heritage Foundation. He previously served as deputy division chief for Korea at the Central Intelligence Agency.