In the midst of succession planning, members of Kim's family, the Korean People's Army and Korea Workers' Party have every incentive to stake out hardline positions — whether for purposes of internal competition or to deter international efforts to destabilize a regime in transition. The bigger picture, however, is that North Korea's behavior is driven by a particularly aggressive nationalism. With its economy a dramatic failure compared to South Korea's, North Korean pride and government legitimacy rely on demonstrations of military power and standing up to exaggerated external threats. North Korea's nuclear weapons and missiles have become integral parts of its national identity.

If an effective international response to North Korea is to be realized, the x-factor is not the outcome of deliberations at the United Nations or the diplomatic tone struck by the United States and Japan. The significant open question is how changing national identities in South Korea and China will inform those governments' interests and policies concerning Pyongyang.

Two previous administrations in South Korea engendered pan-Peninsula nationalism while enshrining democracy at the core of South Korea's national identity. The current administration of President Lee Myung-Bak came to office promising inter-Korean reciprocity and to re-brand South Korea as an innovative economic power. Recent developments challenge these national identity concepts.

North Korea's nuclear and missile tests, the fatal shooting of a South Korean tourist at the Mt. Kumgang resort, the detention of a South Korean businessman at the Kaesong manufacturing complex, and the nullification of various inter-Korean agreements have put pan-Peninsula identity on the defensive.

Meanwhile, the Lee administration's troubled interactions with opposition legislators, organized protesters, unfriendly media, and private citizens who question the government have progressives accusing Lee of turning back the clock on South Korea's hard-earned democracy. Such perceptions proliferated in the wake of former President Roh Moo-Hyun's apparent suicide following a government investigation into his family's financial dealings. Hundreds of thousands of South Koreans have publicly paid their respects to Roh, while criticizing the current leadership for allegedly not understanding South Korea's democratic identity. This adds up to a daunting task for a South Korean president already facing a global recession that hinders his economic goals for the country. As progressives mobilize around Roh's death and conservatives focus on North Korea's provocations, many South Koreans feel they are in a battle for their national soul. Without public support, the South Korean government will have difficulty coordinating policies with the U.S. and Japan. So the main question before Lee's summit with President Obama in mid-June is how well his administration can bridge the divides in South Korean society.

The other major factor for effectively dealing with North Korea involves China's national identity. The ideas of communist revolution and laying low to focus on modernization are becoming obsolete in China. Instead, China covets its traditional role at the center of Asia, entailing not only power, but also respect and responsibility. Such ambition is possible thanks to the success of an economic model that has brought China closer to the U.S., Japan and South Korea. In contrast, Pyongyang's bellicosity and failed economy have left North Korea isolated.

China has long seen its national interests served by the status quo on the Korean Peninsula. According to a Cold War perspective about strategic balance and a post-Cold War emphasis on internal development, Beijing prioritized keeping the Kim regime alive for the sake of maintaining a buffer state and preventing North Korea's problems from spilling over China's border. While Beijing remains fixated on the costs of uncertainty and change, the chances of it “getting tough” with Pyongyang are low. However, China's growing identity gap with North Korea shows signs of changing the way China views its own interests. Political debates inside China now ask whether Beijing underestimates the costs of a nuclear-armed North Korea that threatens regional stability, the reputational costs of being the largest backer of the Kim regime, and the economic costs of a relationship where North Korea takes much from China but respects China little. At the same time, there are questions about whether China overestimates the usefulness of a buffer state, the challenge of North Korean refugees fleeing across the border and the chances of international military conflict on the Korean Peninsula.

The China of today is not the China that came to Pyongyang's aid during the Korean War; its national identity has evolved over decades of rapid development and international integration. Given the country that China wants to become, the costs of maintaining an ally relationship with North Korea may come to surpass the costs of abandoning it.

Pyongyang's nuclear and missile tests reveal not only North Korea's nationalism, but also test how changing national identities in South Korea and China shape strategic interests and ultimately security policy. The extent to which Seoul and Beijing cooperate with Washington and Tokyo hangs in the balance.

Leif-Eric Easley is a Ph.D. candidate at Harvard University's Department of Government, a Visiting Fellow at the University of Southern California's Korean Studies Institute and a Kelly Fellow with the Pacific Forum CSIS.