The North Korean sinking of the Cheonan has left both the South Korean and U.S. governments with a dilemma. There is the strategic and political need to respond to this unprovoked aggression that killed 46 sailors. At the same time, there is little left to take away from an already poor and isolated North Korea. Moreover, there is the real concern that any proportional—i.e., military—response to the attack could trigger a costly, all-out war on the long-divided peninsula.
The administrations of South Korean President Lee Myung-bak and Barack Obama have tried to thread the needle by introducing a series of penalties and criticisms. South Korea has cut off all trade with its neighbor and denied North Korean merchant vessels access to South Korean sea lanes. Diplomats from both countries are busy paving the way for a United Nations Security Council resolution condemning North Korea's aggression and possibly sanctioning it as a result.
Meanwhile, Congress is considering a resolution that would add to the criticism of North Korea. However well-intentioned, it would count for little. If America's elected representatives really want to send a message, they have it in their hands to do so: Pass the Korea-U.S. Free Trade Agreement.
The pact, which makes economic sense for both countries, has been sitting for three years now waiting for congressional action. It is a victim of mostly (although not exclusively) Democratic Party fears that what may make economic sense would hurt politically come November. The Obama administration has not made its passage a legislative priority. But it should be, not simply to create jobs, but to send a much-needed signal of solidarity with an ally at a time of true need.
Even with this action, the problem with the available responses is that they are unlikely to do anything to alter the behavior of the North Korean regime. Efforts to induce or pressure the North into giving up its nuclear weapons and missiles have come to naught. The six party talks designed to bring about denuclearization have not formally met for nearly three years now, and even if they were to reconvene, there is no reason to believe that Pyongyang would give up the weapons it sees as critical to its standing.
So what to do? The next real opportunity to change things for the better is likely to come when North Korea's mercurial tyrant Kim Jong Il departs the scene once and for all time. But positive change will only happen if China acts. If in real estate all that matters is location, location and location, it is only a slight exaggeration to contend that what matters most when it comes to North Korea is China, China and China.
China, however, has been and remains reluctant to use the influence that comes from the fact that the bulk of North Korean trade and energy imports transit Chinese territory and it is China that provides most of Pyongyang's financial links to the outside world. Chinese leaders fear the flood of refugees that would come with North Korean collapse and even more the prospect of a reunified Korean peninsula with its capital in Seoul and lodged squarely within the American strategic orbit.
The good news is that many in China are coming to see North Korea less as an asset and more as the strategic burden that it is. North Korean behavior (such as shown in the sinking of the Cheonan) could easily trigger a war on China's border; North Korean sale of nuclear materials to al Qaeda could trigger an American attack.
This rethinking of what China gets out of its relationship with North Korea may not translate into open Chinese support for a tough resolution at the U.N., but it could well lead to quiet, behind-the-scenes Chinese involvement in North Korea's leadership struggle. China is in a better position than anyone else to increase the odds that Kim Jong Il is succeeded by a reformer who would introduce some market and political changes (call it the Chinese model) and act responsibly towards South Korea and his own citizens.
China has a stake in doing so: to avoid instability on its border, to avoid a crisis that could further roil the region's (and hence China's) economy, and to avoid pressures for nuclear programs in North Korea's neighbors, most notably Japan.
American and South Korean officials need to do more than just point out the risk to their Chinese counterparts of China's current course. They also need to discuss the character of a unified Korea and how one would get there, addressing legitimate Chinese strategic concerns including the questions of non-Korean troop presence and the full denuclearization of the peninsula.
U.S. and South Korean policy should move away from ritualistic calls for resumption of negotiations and toward something far more fundamental: a change in regime in the North that could lead to denuclearization in the short run and Korean reunification over time. In addition, the two governments would be wise to step up their planning for all possible contingencies.
South Korea's president may have signaled an interest in just this on Monday, saying "It is now time for the North Korean regime to change." President Obama should follow suit. There would be no better way to mark this June's 60th anniversary of the Korean war.
Mr. Haass is president of the Council on Foreign Relations and author of "War of Necessity, War of Choice: A Memoir of Two Iraq Wars" (Simon & Schuster, 2009).
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