Abstract: The evidence is clear: North Korea is responsible for the torpedo attack that sank the South Korean naval frigate Cheonan. Now that North Korea’s culpability for this heinous act of aggression has been proven, South Korea and the United States must respond resolutely by imposing a comprehensive package of unilateral and multilateral actions. These sanctions should include severing inter-Korean economic relations, augmenting U.S.–South Korean naval forces and detection capabilities in the West Sea, and insisting that the U.N. Security Council approve a resolution condemning and punishing North Korea.

A multilateral investigative team has concluded that the South Korean naval frigate Cheonan sank as a result of a North Korean torpedo attack. According to the team’s report, strong forensic evidence conclusively “points overwhelmingly to the conclusion that the torpedo was fired by a North Korean submarine. There is no other plausible explanation.”[1] The team was composed of experts from South Korea, the United States, the United Kingdom, Australia, and Sweden.

Now that North Korea’s culpability for this heinous act of aggression has been proven, South Korea and the United States must respond resolutely by imposing a comprehensive package of unilateral and multilateral actions. These sanctions should include severing inter-Korean economic relations, augmenting U.S.–South Korean naval forces and detection capabilities in the West Sea, and insisting that the U.N. Security Council approve a resolution condemning and punishing North Korea.

Results of the Investigation

The Joint Civilian–Military Investigation Group concluded that the Cheonan sank because of a strong underwater explosion generated by the detonation of a homing torpedo below the ship. Technical analysis of propulsion parts—including a propulsion motor with propellers and a steering section collected from the site of the sinking—provided the forensic evidence necessary to assign culpability: The torpedo belonged to North Korea.

Furthermore, Korean characters found inside the propulsion section were consistent with the marking of a previously obtained CHT-02D North Korean torpedo. That torpedo has an explosive warhead consistent with the acoustic signature of the explosion that sank the Cheonan.

Several small North Korean submarines were confirmed to have departed their home base prior to the Cheonan attack and returned after the attack. All submarines from neighboring countries were confirmed to have been either in or near their respective home bases at the time of the incident.

Further Evidence of North Korean Involvement

Additional evidence tends to confirm the accuracy of the Joint Civilian–Military Investigation Group’s conclusions.

• Rodong Shinmun—the official state newspaper of North Korea—announced on March 31, five days after the attack, “Our military and people’s revenge will strike like lightning to bury our enemies in the sea.”[2]
• On April 24, a senior North Korean party leader announced to government officials that the North Korean military took “gratifying revenge” on South Korea.[3]
• Kim Jong-il paid his first visit to the Reconnaissance Bureau on April 25, the anniversary of the founding of the North Korean military. The Reconnaissance Bureau is responsible for conducting espionage and terrorism and is suspected of carrying out the attack on the Cheonan as well as the assassination attempt on North Korean defector Hwang Jang-yop in April 2010.
• Kim Myong-guk, in charge of military operations under the People’s Armed Forces, was demoted from a four-star to a three-star general after North Korea’s November 2009 defeat in a naval skirmish in the West Sea but was returned to four-star status following the Cheonan sinking. Cheong Myong-do, head of the Korean People’s Army operations department, was similarly demoted after the 2009 naval clash and recently returned to full four-star status.
• In February 2010, Kim Jong-il appointed General Kim Kyok-sik, former chief of staff of the People’s Army, to oversee naval operations in the West Sea. Former South Korean President Chun Doo-hwan said Kim Kyok-sik was the chief planner for the 1983 bombing that killed 21 senior South Korean politicians.[4]

North Korean Motives

Most likely, Pyongyang’s attack on the Cheonan was retaliation for North Korea’s defeat in a November 2009 naval clash with South Korea. In that dispute, a North Korean ship was heavily damaged and its crew likely suffered casualties. The Cheonan attack and previous naval clashes took place near a disputed maritime boundary in the West Sea. During the past two years, North Korea has proclaimed that it would adhere to its own interpretation of the military demarcation line, escalated its claim to sovereignty of South Korean waters, increased naval artillery training and augmented ammunition reserves of coastal artillery units in the region, and abrogated the armistice ending the Korean War.

The Cheonan attack was also motivated by Pyongyang’s desire to increase tensions on the peninsula—a negotiating tactic favored by North Korea. Pyongyang has historically seen raising tensions as an effective means of securing negotiating leverage and forcing concessions from its opponents. North Korea typically alternates provocative actions with seemingly conciliatory behavior in order to gain the diplomatic initiative and dictate the negotiating agenda. Given that last year’s long-range missile and nuclear tests did not achieve North Korean objectives, Pyongyang may have felt obligated to up the ante through a high-risk provocative act, such as sinking the Cheonan.

By attacking the Cheonan, Kim Jong-il was likely hoping to force President Lee Myung-bak to soften his principled engagement policy toward North Korea as well as to prompt the U.N. to reduce the sanctions that have had a strong impact on North Korea’s economy.[5] Such a response would hardly be unprecedented; Pyongyang has often lashed out when it felt weak or was perceived as weak by opponents in what South Koreans refer to as the “barking of a wounded dog.”

Despite the audacity of attacking a South Korean ship, Kim Jong-il would have been confident that neither South Korea nor the U.S. would retaliate militarily. Both countries have suffered several North Korean attacks that led to loss of life, but neither has retaliated.[6] Nor was Pyongyang punished when it brazenly violated the U.S. redline against nuclear proliferation when it helped to build a covert nuclear reactor in Syria.

Seoul Angry, But Not Angry Enough to Attack

After disclosing evidence of North Korea’s attack on the Cheonan, Seoul will feel compelled to respond with punitive measures. However, South Korea will not conduct a military attack. The populace is angry, but not angry enough to advocate military strikes against North Korea since such an attack could escalate into all-out war and the subsequent collapse of the North Korean regime.

War and its attendant consequences would jeopardize Seoul’s two highest priorities: ensuring economic recovery and hosting the G-20 summit. Even a series of tactical-level inter-Korean clashes could spook investors and have a dramatic impact on the South Korean bourse and economy. The G-20 summit is seen as another manifestation of South Korea’s recognition as an important international nation, similar to the 1988 Seoul Olympics.

President Lee Myung-bak may have intended his April meeting with former Presidents Kim Young-sam and Chun Doo-hwan to provide political cover for not responding militarily. Kim and Chun were conservative presidents who talked tough about North Korea but did not respond to North Korean attacks during their administrations. As a result, there is less pressure on President Lee to respond with military force.

China Remains the Weak Link in Campaign to Punish Pyongyang

Fearful that a resolute response could trigger North Korean instability or even collapse, thereby replacing a buffer state on its border with a powerful reunified Korea, Beijing will react with its customary call for caution and restraint. In fact, Chinese Defense Minister Liang Guanglie has already commented that “even when the final result [of the investigation] is out, it is necessary to deal with it in a cool-headed and prudent way for the peace and stability on the Korean Peninsula.”[7]

In order to prop up Pyongyang, China is willing to hinder the effectiveness of international sanctions by providing economic benefits to North Korea outside of the conditionality of the Six-Party Talks. By not fully implementing sanctions and by offering alternative sources of revenue, Beijing reduces the likelihood that North Korea will return to the Six-Party Talks. After all, why would Pyongyang seek the conditional benefits offered as inducements in the nuclear negotiations when it can receive the same benefits directly from China?

However, China can be moved beyond its comfort zone, albeit grudgingly and not as far as Washington would prefer. For instance, Beijing acquiesced to U.S. pressure to impose sanctions on North Korea after the 2006 and 2009 nuclear tests. A blatant North Korean provocation—such as the sinking of the Cheonan—could provide South Korea and the U.S. with sufficient leverage to get Beijing to agree to some stronger measures against North Korea. Washington and Seoul should press Beijing strongly in the U.N. Security Council to impose a suitable punishment on North Korea.

What Needs to Be Done

Seoul and Washington should punish North Korea by imposing a comprehensive package of unilateral and multilateral actions.

Specifically, South Korea should:

• Terminate all economic engagement with North Korea. Economic restrictions should remain in place until North Korea admits its culpability for the Cheonan incident, apologizes, takes punitive measures against those individuals directly responsible, offers reparation and compensation, and takes measures to prevent a recurrence. For example:

1. Suspend the purchase of all North Korean products, including agricultural products, natural resources, and seafood. South Korea is Pyongyang’s second largest trading partner, accounting for 30 percent of North Korea’s overall trade. Cutting inter-Korean trade would therefore have a major impact on North Korea’s economy.
2. Shut down the Kaesong business venture, which provides 63 percent of inter-Korean trade.[8] Kaesong was the flagship of liberal South Korean administrations’ “sunshine policy” of economic engagement with the North. But this joint Korean industrial zone foundered after North Korea tried to extort additional concessions and confiscated South Korean assets at the Kumgangsan tourist venture.[9] South Korea should seize the initiative and scuttle this doomed venture.

• Review South Korea’s defense posture. North Korea’s ability to inflict grievous injury on South Korea’s military should counter misperceptions that North Korean intentions have become less hostile or that engagement has moderated Pyongyang’s behavior. Therefore, Seoul should:

1. Reassess Defense Reform Plan 2020, which was predicated on a declining North Korean threat that would enable South Korea to reduce its conventional forces. Seoul should reassess planned changes in its force posture to include both an enhanced near-term priority on deterring and defending against North Korean conventional forces and long-term objectives for expanding its regional security role: for example, by building a blue-water navy and developing an indigenous AWACS reconnaissance plane.
2. Increase defense spending and accelerate programs to respond to North Korean conventional forces. Seoul should improve its C4ISR[10] capabilities and crisis management response system.
3. Augment South Korean naval forces and detection capabilities in the West Sea. Enhance sensors near the maritime boundary to better detect intrusions by North Korean submarines and covert infiltration boats.
4. Declare that any North Korean submarine detected south of the Northern Limit Line (NLL) will be sunk without warning.
5. Initiate combined U.S.–South Korea anti-submarine and mine-clearing naval exercises near the NLL area.

For its part, the U.S. has its own role to play and should:

• Support South Korean efforts for a new U.N. Security Council resolution condemning North Korea’s attack on the Cheonan. It is absolutely critical that the Obama Administration fully support America’s South Korean ally during this time of crisis. There must be neither daylight between Washington and Seoul nor any perceived differences in the bilateral response to Pyongyang’s blatant act of aggression.
• Press the U.N. Security Council to close the loopholes in Resolution 1874, such as adding measures to enable military means to enforce the sanctions. Doing so would prevent recurrences of the Kang Nam incident in which the U.S. Navy was prevented from boarding a North Korean ship suspected of proliferating proscribed items.
• Insist that all nations fully implement U.N. sanctions to prevent North Korean procurement and export of missile- and WMD-related components and freeze the financial assets of any complicit North Korean or foreign person, company, bank, or government.
• Advocate targeting foreign companies, banks, and governments that assist North Korea’s nuclear and missile programs. The Obama Administration and the international community have been reluctant to target the other end of the proliferation pipeline, preferring to focus only on North Korean noncompliance. However, it is past time to identify and target other violators of U.N. Resolution 1874 such as Burma, Syria, and Iran.
• If the U.N. is reluctant to do so, Washington should impose unilateral sanctions on foreign entities engaged in proliferation and call on other nations to match the U.S. effort. Such action has the benefit of not being subject to Chinese veto or foot-dragging.
• Lead a global effort to vigorously enforce international law against North Korean illegal activities, including counterfeiting of currency and pharmaceuticals, illegal production and distribution of narcotics, and money laundering. Orchestrate an international effort to interdict North Korean ships suspected of violating U.N. resolutions or international law.
• Condition the resumption of Six Party Talks on resolution of the Cheonan incident. North Korea cannot be allowed to benefit from its attack on the Cheonan simply by agreeing to return to the nuclear negotiations.
• Return North Korea to the state sponsors of terrorism list. Pyongyang’s attempted assassination of Hwang Jang-yop and arms transfers to terrorist groups would more than justify such an assignment. Indeed, there is no shortage of evidence linking North Korea to state-sponsored terrorism. For example, two North Korean agents confessed to South Korean authorities that they attempted to assassinate Hwang Jang-yop, the highest-ranking North Korean official ever to defect to the South. They stated that they had received their order from Kim Young-chol, chief of the Reconnaissance Bureau.[11] Israeli Foreign Minister Avigdor Lieberman stated that North Korean weapons seized in Thailand last year were headed for Islamist groups Hamas and Hezbollah.
• Review the OPCON transfer agreement. The U.S. and South Korea should jointly assess whether the Cheonan attack calls into question the scheduled 2012 transfer of wartime operational command of South Korean forces from the U.N. commander to Seoul. More important, the U.S. Congress and Korean National Assembly should hold hearings to determine whether dissolving Combined Forces Command and establishing parallel commands undermines alliance deterrence and defense capabilities.
• Demand a suspension of all U.N. Development Program activities in North Korea until Pyongyang complies with U.N. Security Council resolutions. Demand that North Korea agree to rigorous, transparent monitoring standards and delivery verification for all international food and humanitarian assistance.

Waiting for the Other Shoe to Drop

It is likely that the Cheonan sinking is not a singular event but rather the beginning of a North Korean campaign to raise tensions on the Korean Peninsula. A greater willingness to engage in high-risk behavior could be the result either of North Korea’s growing confidence due to its nuclear weapons status or, conversely, its growing desperation resulting from the increasing impact of international sanctions on its economy.

It can be expected that North Korea will react strongly to any international effort to punish it for the Cheonan attack. Pyongyang could even be looking for a strong international response to the Cheonan sinking in order to justify additional belligerent behavior. Similarly, North Korea may have planned on triggering a U.N. response to its April 2009 long-range missile test in order to justify its nuclear test the following month. If that is the case, North Korea will engage in additional provocative behavior, particularly in the run-up to Seoul’s hosting of the G-20 summit in November.

Bruce Klingner is Senior Research Fellow for Northeast Asia in the Asian Studies Center at The Heritage Foundation.