President Lee Myung-bak wants South Korea to develop longer-range ballistic missiles to better protect his country against North Korea’s arsenal according to media reports in the South. Considering the existing combined U.S.-South Korean capabilities, the added military value of the missiles is marginal, but their political impact could be major. The move could have profound implications for the security environment in the region, especially for Japan. Seoul should give careful thought to the potential impact of such a dramatic move. In the absence of further provocation from North Korea, significantly longer-range missiles are not the best solution to the problems currently facing the region.

Japan, which on its own has no means to respond to missiles fired at its territory, is the country most at risk, but not for the reason many think. The Chosun Ilbo quoted an anonymous source saying that Tokyo has a “negative attitude” toward President Lee’s initiative. The stated reason—that the new missiles could range over much of Japan—is a red herring. That is like suggesting South Korea should fear Japan’s aerial refueling capability because it could allow for attacks on Korea. Given the near-complete alignment of these countries’ interests and their alliances with the United States, neither scenario is worth considering.

The important question for Tokyo is the new missiles’ impact on the overall regional security environment—will there be backlash in North Korea, China, and Russia that could undermine Japanese national security? It is the potential fallout from South Korean missiles, not the missiles themselves, that concerns Tokyo.

If the South Korean government is serious about building new missiles, then Seoul must take these considerations into account. It should reach out proactively to Tokyo and other neighbors to explain its rationale and consider shorter ranges to minimize potential blowback.

On the surface, these developments may not seem all that significant given the Peninsula’s history. It is no secret that some South Korean politicians and policymakers have long worried about North Korea’s short-range missile inventory, now over 500 strong and able to strike any part of the Korean Peninsula. Despite this, Seoul joined the Missile Technology Control Regime in 2001 and decided to restrain its own missile development to just under the regime’s Category 1 parameters (that is, those capable of carrying a 500 kilogram payload at least 300 kilometers, space launches excepted). This has become an important—though not universal—benchmark internationally as a means to limit the proliferation of more destabilizing long-range missile systems around the world.

The existing combined might of U.S. and South Korean forces—notably in the form of superior airpower on Peninsula backed by U.S. air and naval forces stationed in Japan—is certainly adequate to defeat North Korea if necessary, even if South Korean ballistic missiles cannot reach targets up near the Chinese and Russian borders. The North’s ongoing nuclear program, however, raises the stakes significantly for Seoul, both militarily and politically.

South Korean leaders are seeking to do everything they can to address that threat, including investing in cruise missile upgrades and considering new investments in intelligence, surveillance, and reconnaissance assets, so that missiles in the far North can be identified and targeted as needed. Seoul is also looking to modernize its fleet of attack aircraft with stealth technology and invest more in domestic missile defenses. All of these are prudent defensive measures in light of North Korea’s unrestrained missile and weapons of mass destruction programs.

However, Seoul’s desire to acquire longer-range ballistic missiles is another matter entirely. The Lee government is reportedly interested in building new missiles with a range up to 800 kilometers, which would represent a qualitatively different and counterproductive approach to addressing North Korean threats.

In response to the new missiles, North Korea and other nations could take countermeasures that might put Japan even further behind in a regional arms race. For example, North Korea could choose to ramp up production of short- and medium-range missiles to counter the South Korean move, and Pyongyang might solicit Chinese political or technical support for its program, given Seoul’s new “provocative” policy approach. China would be reluctant to violate United Nations sanctions on this front, but the central government’s commitment to enforce these sanctions could weaken as South Korea clouds the issue of who is the provocateur and builds missiles essentially targeting China’s border region. To protest the South Korean move, Beijing could more actively frustrate diplomatic initiatives aimed at North Korean denuclearization or go so far as to increase its own stock of missiles capable of reaching South Korea (which would cover Japan by default).

Moreover, Russia has long denied itself intermediate- and shorter-range missiles through the 1987 Intermediate-Range Nuclear Forces Treaty with the United States. Although negotiated with Europe in mind, the treaty also prohibits missiles that could hold South Korea (and Japan) at risk. This is not a problem for Moscow as long as South Korean missiles cannot reach its territory, but Russia could use the changing strategic dynamic on the Peninsula to justify reconsideration of the treaty, thus undermining a twenty-five-year-old disarmament initiative and adding one more nation to the list of countries that can target Japan with missiles. Additionally, since the primary military value of longer-range South Korean missiles is presumably their ability to strike North Korean targets quickly and preemptively, the risk of a serious military escalation if conflict erupts will increase.

And though almost two-thirds of missile-fielding countries in the world currently respect the 300 km/500 kg limit, South Korea’s disregard for this standard could lead to further erosion of restraints on long-range missile proliferation around the world. Japan would also have to consider whether the North Korean missile threat is suddenly so urgent and so grave that it should augment a defensive approach with its own strike capability.

No one can deny that both South Korea and Japan face a unique threat from North Korean WMD, but that does not mean building longer-range missiles to lob back at the North is a militarily useful, cost-effective, or strategically prudent response at this time. Although South Korea is within its rights to develop longer-range missiles, Seoul’s reported proposal to build 800-km-range missiles is excessive and could spark a backlash that makes U.S. allies less secure in the long run. The specific threat these new missiles would address is too narrow at this point to warrant the diplomatic and financial cost, especially while the U.S.-South Korea alliance maintains such a capable and versatile military force.

Absent further nuclear or missile tests by the North that suggest a more sophisticated threat, a new ballistic-missile program in South Korea is premature and would drain valuable funds away from more practical and important intelligence, surveillance, and reconnaissance efforts and military command and control investments needed in the near term. It could also weaken international pressure on the North and could undermine the solidarity of U.S. allies in Northeast Asia on issues related to North Korea.

Alliance solidarity and continued international pressure (that includes China and Russia) are still the best ways to counter North Korean belligerence. The allies could put North Korea (and China) on notice, however, that future tests by the North would cause reconsideration of the South’s ballistic-missile position. After all, North Korea cannot be allowed to perfect its missile and WMD technologies without any response, and South Korea has already ceded the North a long head start in missile development.

If South Korea finally decides that it can no longer wait, then a shorter-range missile program is preferred (closer to 500 km), since this will avoid targeting Chinese or Russian territory while still covering all of North Korea. This will mitigate at least some of Japan’s likely concerns, and America’s as well. Even though this latter scenario would break the Missile Technology Control Regime Category 1 threshold, it is a decidedly restrained response in the face of North Korean threats, and it should help keep international pressure on North Korea, where it belongs. U.S. and its allies could also step up information sharing to help disrupt the North’s programs and improve targeting in case of conflict.

Amid recent South Korea-Japan diplomatic friction over territory and history, it might be tempting for Seoul to downplay or dismiss Tokyo’s concerns, but this obscures the potentially adverse impact on South Korea’s own interests. It also ignores the need for both countries to separate bilateral disputes from matters of mutual national security.

The fact remains that U.S. bases on Japanese territory and Japan itself are critical for the defense of South Korea in any major conflict on the Peninsula. Separating politics from national security does not prejudice any steps Seoul and Tokyo might take to address their political differences in the future. But it can help ensure stability, prosperity, and security for the region.