South Korea will announce on May 20 the results of its investigation into the explosion and March 26 sinking of the navy corvette ChonAn (772). South Korean media has been full of leaks from defense and government officials indicating that all evidence points to a North Korean torpedo being responsible for the sinking. Seoul has been cautious about laying the blame formally on Pyongyang until it had enough evidence and intelligence to clearly link the explosion to North Korean actions, as South Korean officials wanted to ensure Chinese cooperation with whatever punitive actions result from the investigation. Seoul has already begun sharing its findings with allies and other key countries involved in the North Korean issue. South Korean President Lee Myung Bak called U.S. President Barack Obama on May 18 to discuss the findings, and the South Korean government has talked with the Japanese, Chinese and Russians, and is holding briefings for foreign embassy officials. According to leaks from South Korean and foreign officials, Seoul will formally blame North Korea for the attack on the ChonAn, something long expected as the investigation proceeded. For South Korea, the question, however, has been less one of responsibility for the sinking than what to do next. Despite initial confusion, Seoul quickly ruled out a friendly fire incident or internal explosion, leaving a North Korean sea mine or torpedo as the probable cause. Soon thereafter, South Korean defense and intelligence officials began to leak reports of North Korean submarine activity the night of the incident, of changes in North Korean submarine training programs, and of initial speculations and findings in the investigation — all pointing to North Korean culpability. Reports have since emerged that Seoul has matched explosive residue on recovered sections of the ChonAn to the explosives found in a stray North Korean torpedo captured years earlier, that pieces of the torpedo screw were found that match a type originating from China or the Soviet Union and used by North Korea, and that a piece of a serial number with North Korean font has been found. Seoul's delay in laying blame has more to do with offering clear proof for diplomatic purposes than with any doubt over the cause. But the response is another story. The concerns for war, particularly with nearly half the population of South Korea concentrated in the greater Seoul-Inchon area and within range of North Korea's front-line artillery, have long limited South Korea's responses to North Korean provocations. While there were scattered calls from South Korea for a military response, Seoul quickly ruled that out, due to the potential for a rapid escalation of tit-for-tat retaliations that could trigger a full war on the Peninsula, one where North Korea could even possibly deploy its nuclear devices. Seoul was further urged by Washington to take a less aggressive approach to the incident, initially to avoid overshadowing Obama's unannounced visit to Afghanistan on March 28, but also to avoid triggering a major confrontation. Instead, South Korea is looking at political and economic responses in the near term, with a longer-term focus on a change in the country's defense capabilities and posture. Seoul's first step was to encourage South Korean businesses currently conducting operations or trade with North Korea to cease new orders or expansion. Seoul also encouraged importers of North Korean goods, including sand and marine products, to stop. The government also plans to cut all funding for inter-Korean projects, aside from humanitarian aid and the Kaesong joint economic zone, and reapply restrictions on North Korean ships passing through South Korean waters, particularly through the Cheju Strait. The Kaesong zone has been particularly troubling for South Korean officials. Kaesong is the centerpiece of Seoul's more than two-decade-old policy of trying to strengthen the economic infrastructure of North Korea to ease the pains of potential future reunification. It also serves as a visible example of lowered tensions on the Korean Peninsula, something Seoul can point toward to allay concerns of foreign investors. But as early as March 2008, North Korea began to target the Kaesong zone, expelling South Korean officials and continuing to pressure the South Korean operations there, declaring all agreements null, demanding pay increases, blocking transit for South Koreans out of the zone, and threatening the seizure of all assets. Seoul, in response, worked even harder to keep the operations open. In retrospect, whether the North Korean actions were triggered by internal factional struggles or the rising power of the military, the actions removed a potential economic lever from the South Korean playbook. North Korea has done more to interfere with Kaesong than the South, and Seoul has determined that, despite other sanctions and punishments, it is vital to try to keep at least the Kaesong project operational. Seoul hopes to have a real impact on the North economically through the international community via the United Nations — but this requires Chinese cooperation. China has been reticent to accuse North Korea of the attack, and Chinese officials have publicly called on Seoul to carry out the investigation in an objective manner and not jump to conclusions. Beijing's hosting of Kim Jong Il in early May, and the new Chinese ambassador to Seoul's decision to hold a meeting with the opposition Democratic Party — which has been critical of the ChonAn investigation — rather than with ruling party officials has raised further concern in Seoul of Beijing's objectivity. Seoul has thus been working to provide "irrefutable" proof of North Korean responsibility before sending its finding to the United Nations. Sanctions in the best of times do little, and without Chinese participation, they can be expected to do even less. Seoul wants targeted sanctions against specific regime members and military accounts overseas, with international pressure dissuading any further investment by third countries in North Korea. Pyongyang has recently launched an investment drive to attract mining, manufacturing and infrastructure development investments, particularly from Europe, the Middle East and South Asia. Interest has not been strong, and Seoul intends to use the sanctions to further weaken any potential revenue flowing to the North. The economic strictures overall are expected to have a minimal impact, as North Korea is already under economic sanctions, and the country's international trade remains small. In many ways, the sanctions are for show, domestically and internationally, and highlight the limits of South Korea's options. But there are changes afoot in South Korea that are triggered off of the ChonAn incident. President Lee has called for a review of Seoul's defense posture, reassessment of the Defense Reform 2020 plan, and a 3 trillion won ($2.6 billion) increase in weapons development and procurement spending. Among the ideas being discussed are joint South Korean/U.S. anti-submarine warfare exercises in the West (Yellow) sea later this year (possibly involving a U.S. nuclear submarine); upgrades to sonar and radar systems; the deployment of a Sound Surveillance System (SOSUS) along the Northern Limit Line; and in the West Sea, a network of acoustic anti-submarine sensors that can greatly improve South Korean underwater situational awareness. These mid- to long-term initiatives fit within a broader pattern already under way in South Korea to improve its naval capabilities, but the ChonAn incident has given impetus and urgency to the moves. While the changes in Seoul's West/Yellow Sea defense capabilities are ostensibly targeted toward North Korea, however, they are likely to raise concern from Beijing. The Chinese People's Liberation Army Navy (PLAN) North Fleet, headquartered in Qingdao, has responsibility for the Yellow Sea. Qingdao is also home to the Chinese submarine academy. The PLAN has considered moving its more modern warships and submarines to the East Fleet and South Fleet, as they become more important for Chinese naval strategy, but the Yellow Sea still represents the naval approaches to Beijing, and remains a sensitive location for the Chinese military. The prospect for increased South Korean surveillance, naval activity and joint operations with the United States is already raising concerns in Beijing, and may trigger China to reassess its plans for naval reorganization, which was intended to focus more heavily on the South China Sea and the maritime routes through the Strait of Malacca and the Indian Ocean to the East African coast and the Middle East. Seoul's response to the ChonAn incident, then, may do less to punish North Korea than it does to add speed and justification to wide-reaching South Korean military reforms that could quickly cause alarm in China, which is already watching South Korean and other U.S. allies' naval operations in the Asia-Pacific region.