It is important to understand not only how missile defense works to limit the damage of an attack from the North, but also how it functions to generally enhance deterrence.
Its role in enhancing deterrence is important for a couple of reasons.
First, if THAAD enhances deterrence it prevents other means of attack (artillery fire, ground trop invasion, bomber attacks) that Con teams will argue that missile defense cannot solve.
Second, it provides strong general refutation for the claim that, “deterrence solves.” If a loss of missile defense undermines deterrence, then the Con’s deterrence arguments are substantially weakened.
So, that said, let me explain the reasons missile defense enhances deterrence.
One, even if missile defense is not 100% effective, it is able to shoot-down enough missiles that US and South Korean retaliatory capabilities will survive.
Sutyagin, 8-21, 17, Sutyyagin is the author of Margaret Thatcher and the Middle East (Cambridge University Press, 2016). IGOR SUTYAGIN is Senior Research Fellow at the Royal United Services Institute, August 21, 2017, Foreign Affairs, Moving Forward With THAAD, https://www.foreignaffairs.com/articles/south-korea/2017-08-21/moving-forward-thaad
The U.S. missile defense program is more rightly viewed as a hedge against deterrence failure. China’s complaints over THAAD are wrong-headed since North Korea poses a grave and immediate threat to South Korea and Japan. By deploying missile defence systems in East Asia, the United States is reinforcing its security commitments to its allies in the region. In view of the fact that some 11 million people live in Seoul (one in five South Koreans), which is just 35 miles from the border with North Korea, they are vulnerable to an attack from Pyongyang. Thus a U.S. security commitment must utilize all the resources at its disposal to protect its ally, exemplified through missile defense. If there are no systems in place to intercept a North Korean missile barrage, many hundreds of thousands could be killed. In such a scenario, the United States would struggle to minimize the scope of the conflict, amid the suffering in South Korea. This is known in the field as “deterrence by denial”: THAAD cannot provide cast-iron guarantees but it sends the message to Pyongyang that the success of a missile barrage against South Korean cities is not guaranteed either….Pyongyang must consider the strong probability that Seoul’s retaliatory capabilities would survive intact as a result of the defensive system.
Keith Payne, a nuclear deterrence theorists, wrote in the Fall of 2017, that, “The deployment of THAAD to South Korea, for instance, will help protect the survivability and credibility of US and ROK retaliatory forces” (Strategic Studies Quarterly)
Two, most US troops are deployed in Seoul and the DMZ along the border – approximately 25,000 of them. These troops function as a “tripwire” that would force the US into the conflict (US politicians would have no choice to intervene if 25,000 US soldiers were killed), but no one thinks that many (or any) of them would survive. They merely exist to slow the North’s advance a bit and to send a credible signal that the US would get involved in the war. The North has a 1.6 million person army and there is no way those 25,000 troops can hold that off.
But, then, how do South Korea and the US win the war? Well, first, remember that if missile defense can protect some assets, we have short-term retaliatory capabilities.
We also have 50,000 troops stationed in Japan. Those troops would redeploy to South Korean in the event of a war and would enter into the south of the country, fighting their way North. If the North launches a nuclear attack on the southern part of Korea, however, the US would not be able to redeploy these troops. This is one of the key reasons the US wants THAAD in the southern part of South Korea – to protect the redeployment of our troops.
If Kim knows our troops can’t redeploy, deterrence will be undermined.
Bennet, 8-6-17, Bruce W. Bennett is a senior defense analyst at the nonprofit, nonpartisan RAND Corporation, Why THAAD is needed in Korea, https://www.koreatimes.co.kr/www/opinion/2017/08/197_234268.html
The United States selected South Korea for its second THAAD deployment because North Korea poses missile threats greater (in character and likelihood of use) than those the United States faces anywhere else in the world. There were many reasons for the deployment of THAAD in Seongju, the location chosen for the THAAD battery in South Korea. One leading reason: In a major Korean conflict, tens of thousands of U.S. military personnel would deploy to Korea over time largely through the Pusan port area in southeastern Korea. They would be most vulnerable to a North Korean nuclear weapon attack while in the port area and while assembling to depart from Pusan. Not protecting exposed military personnel from the North Korean ballistic missile and nuclear weapon threat would be irresponsible, the United States concluded. By placing THAAD in Seongju, the U.S. can also attempt to protect the large South Korean urban areas of Pusan, Kwangju, Pohang, and Daegu, as well as many other cities in the southern part of South Korea. During a U.S. military deployment to protect South Korea, a North Korean nuclear weapon detonating on Pusan might kill thousands of U.S. military personnel arriving in Pusan, but it could also kill a 100,000 or so South Koreans. With this THAAD placement, the United States is trying to prevent such an outcome. THAAD’s successful intercept of an intermediate-range ballistic missile in July demonstrated U.S. ability to potentially stop the North Korean theater ballistic missiles.
Three, deploying THAAD is important to US-South Korean relations. A decision not to deploy it would substantially hurt relations.
Sarah Kim, 6/27/17, Thaad is elephant in the room at US summit, http://koreajoongangdaily.joins.com/news/article/article.aspx?aid=3035101 ST
While China often complains about Thaad’s over-the-horizon radar,” he continued, “China has reportedly deployed three similar radars in the area surrounding the Korean Peninsula. Why is it okay for China to have these systems, but seriously destabilizing if South Korea deploys but one Thaad battery?”“Beijing is pressuring Seoul to come up with a political decision, because we are providing it pretext to do so,” said Chung Jae-hung of Sejong Institute. Chung pointed out, “Thaad is a linchpin in the Korea-U.S. alliance, an important stage in the United States’ missile defense (MD) system. So in China’s position, Seoul withdrawing from Thaad will be a considerable strategic blow to the trilateral security cooperation between South Korea-U.S.-Japan and the MD system being pushed for by the United States.” Should Korea decide to scrap the deployment of Thaad, he pointed out, “U.S. influence in the Asia-Pacific region cannot help but decrease, and Beijing, from its viewpoint, would then be able to expand its influence in this region, enabling China to exercise its influence in this area much more assertively.” The Moon administration also aims to revive inter-Korean talks, and China’s support would play an important role in that process.
Why:? Remember that in the spring Trump really pushed Moon to support deployment of THAAD even though Moon was originally not very supportive because he knew it would alienate China and provide limited protection for South Korea. But Trump pushed this because he knew it was important to protecting US troops. If South Korea was not willing to protect US troops, that would undermine support in the US for protecting South Korea:
Forbes July 21, 2017, https://www.forbes.com/sites/scottasnyder/2017/06/11/south-koreas-decision-to-halt-thaad-carries-hidden-risks/#5e5a06f429ad
The Moon administration must find a way to enhance governmental transparency and accountability while upholding its credibility as a strong U.S. security partner. If the perception becomes that the South Korean government is blocking measures necessary to protect American forces, that would rapidly erode American public support for U.S. troop commitments. It could potentially provide President Donald Trump with a pretext to pursue U.S. withdrawal of forces in Korea.
Moon’s decision also carries another risk. For months, China put the economic pressure on South Korea for agreeing to the deployment in the first place.
So, if Moon bailed on deployment now, that would really hurt relations.
Strong South Korea-US relations have sent a strong deterrence signal to the North and have prevented the outbreak of war for years –
Evans Revere 2016 explains that
Evans Revere, Brookings, November 2016, The U.S.-ROK Alliance: Projecting U.S. Power and Preserving Stability in northeast asia. https://www.brookings.edu/wp-content/uploads/2016/11/fp_20160713_korea_alliance1.pdf
The powerful deterrent provided by the U.S.-Republic of Korea security alliance has kept the peace on the Korean Peninsula for over 63 years. Today, with the rising threat of a nuclear-armed, aggressive North Korea, growing friction in U.S.-China relations, and rapidly changing security dynamics in the Asia-Pacific region, the U.S.-ROK security alliance is more important than ever and a pillar of America’s ability to project military power, deal with uncertainty, and maintain stability in a region of vital importance to American interests. The 28,500 U.S. forces in Korea demonstrate America’s determination to defend a key ally and reflect U.S. commitment to the region at large. Nurturing and strengthening the alliance relationship — which has served U.S. interests well — will be a central task for the next U.S. president. This will be particularly true in light of growing concerns in the region about America’s staying power, worries about neo-isolationist trends in the United States, and fears about China’s attempt to become the region’s dominant actor. Another challenge will be South Korean politics, where a victory by the center-left in the 2017 presidential election could bring to power forces critical of the alliance, sympathetic to China, and inclined to adopt a softer line towards North Korea. Korea’s Stake in the Alliance Despite the ROK’s lead in technology, training, and modern equipment, North Korea enjoys numerical superiority in terms of troops, tanks, artillery, and aircraft. The bulk of North Korean forces are forward deployed near the demilitarized zone, enabling them to strike the South quickly and with considerable effect in the event of a conflict. The South Korean capital and a major portion of its population are within long-range artillery and tactical rocket range of the Korean People’s Army (KPA). North Korea has in recent years carried out an artillery attack on a South Korean island, sunk a ROK Navy corvette in South Korean waters, and frequently threatens to turn Seoul into a “sea of fire.” For South Korea, the North’s threat is real and deadly. The U.S.-ROK alliance provides the confidence and military capabilities necessary to deal with it, especially as the DPRK tries to overcome its qualitative disadvantage by developing dangerous new asymmetric offensive capabilities. In the event of war, South Korea would provide the bulk of forces to counter the North. While the ROK’s military has grown increasingly sophisticated, the capabilities that the United States would bring to bear in a conflict would be essential to an allied victory. …..component of alliance cooperation. The ROK has largely focused on indigenous systems, while also seeking to ensure maximum interoperability with U.S. missile defense systems. In response to a U.S. request, Seoul has agreed to discuss eventual deployment of Theater High-Altitude Area Defense (THAAD) by the United States. This deployment would greatly enhance the alliance’s ability to intercept and destroy North Korean missiles and set the stage for broader U.S.-ROK missile defense cooperation, including coordination with Japan-based systems aimed at countering North Korea. The U.S.-ROK alliance works. In the event of war, North Korean aggression against the ROK would be met with a strong and immediate response. …..
Cementing our allied relationship is needed to prevent North Korean coercion and the failure of diplomacy. Wallace Gregson explains on August 12 that
Gregson, 8-12-17, Wallace C. Gregson is a retired Marine, former assistant secretary of defense for Asian and Pacific Security Affairs 2009–11, currently senior advisor at Avascent International and senior director for China and the Pacific at the Center for the National Interest, North Korea comes armed, barricaded with hostages, http://nationalinterest.org/feature/north-korea-comes-armed-barricaded-hostages-21871
Regime change could follow a failure of the system of sharing spoils and privilege. That is not an acceptable risk. As a result, China will only apply limited pressure to North Korea. Given the repeated failure of our three traditional responses—military preemption, negotiations over agreements, and enforcement of sanctions—we must shift focus to our allies and friends. They are the most important element now. We must act to reinforce the credibility of our deterrence, a deterrence that has been under assault since the early 1990s. Our assurances that agreements and sanctions will work have been exposed. The very existence and success of North Korea’s missile and WMD programs—recall the successful deployment and employment of VX nerve gas in Malaysia—is eloquent testimony to sanctions and agreement failures. We need a different approach. Credible deterrence is built upon an undoubted ability to prevail in the event of conflict. This is not seeking conflict, any more than establishing effective law enforcement or fire prevention is encouragement of crime or fire.
Kim will see a weakening of the alliances as a reduction of the willingness of the US to defend Korea, causing him to rationally conclude that war is winnable.
Financial Times, September 5, 2017, https://www.ft.com/content/71402212-91e0-11e7-a9e6-11d2f0ebb7f0
“If Mr Kim dreams of refighting the Korean war, any indication of weakness in the US-South Korea alliance will encourage him.” North Korea now has ICBMS and hydrogen bombs. Why would we risk LA to save Seoul if the alliance collapses? Nicholas Eberstadt, a Korea expert at the conservative American Enterprise Institute think-tank, is among those who believe that North Korea’s ultimate aim is to fight and win a war with the South. “If Pyongyang can force an American president to blink in a future Korean crisis, then the US-South Korea military alliance will collapse,” he says. “US forces will be out [of South Korea] and the Kim family regime will take a giant step to settling the still unfinished Korean war on its terms.” Fears over such a scenario are growing in South Korea, where citizens have begun to question whether the US is truly ready to defend its longstanding ally in the face of a nuclear-armed adversary.
Fourth, as noted in the Kim evidence above, the THAAD is also important to trilateral defense cooperation between the China, Russia, and the United States. This trilateral defense cooperation is also important to de-escalating the crisis.
Easley explains on September 3rd that
Easley, 9-3-17, Leif-Eric Easley is assistant professor in the Division of International Studies at Ewha Womans University and an international research fellow at the Asan Institute for Policy Studies in Seoul., Foreign Policy, North Korea’s missile tests are aimed at splitting its rivals, http://foreignpolicy.com/2017/09/03/north-koreas-tests-are-aimed-at-splitting-its-rivals/
In addition to advancing its military capabilities, Pyongyang’s missile and nuclear tests have the diplomatic goal of driving wedges among the United States, its allies, and China. The Kim regime seeks to divide its neighbors to extract concessions, bust sanctions, and forestall increases in coordinated pressure. Yet if the United States strengthens trilateral cooperation with Japan and South Korea, it can counter Pyongyang’s threats and encourage China to force North Korea back to denuclearization talks…. Such trilateral unity would show that Pyongyang’s nuclear and missile programs have failed to divide Washington, Seoul, and Tokyo, and would give Beijing an opportunity to make credible a diplomatic option that all parties prefer to military escalation.
Fifth, without strengthening our defenses, the US doesn’t have any leverage in negotiations with the North. We need this leverage to get them to negotiate
Abraham M. Denmark served as deputy assistant secretary of defense for East Asia from 2015 through January 2017, Foreign Policy.com, The US Can’t Get Rid of North Korea’s nukes without paying a catastrophic price, http://foreignpolicy.com/2017/09/15/the-u-s-cant-get-rid-of-north-koreas-nukes-without-paying-a-catastrophic-price/
Finally, preventative war is highly unattractive for the United States and its allies, because of North Korea’s ability to kill potentially millions of South Koreans, Japanese, and Americans. While the United States would ultimately be successful in a conflict with North Korea, in all likelihood that victory would come at a horrendous cost. Pyongyang knows this and does everything it can to emphasize the costs of war, which means that threats to attack North Korea therefore are likely to ring somewhat hollow to Pyongyang. This fundamentally undermines every attempt to negotiate with North Korea, as it severely diminishes U.S. leverage over what Pyongyang values most — its own survival. Given the remarkable pace of successes North Korea has seen in recent days and weeks, and the inability of the United States and the rest of the international community to convince Pyongyang to choose a different path, the implication is clear: The United States will likely have to live with a nuclear North Korea. This does not mean we should accept it. Nor does this mean we should abandon efforts to convince North Korea to give up nuclear weapons. But it does mean that the United States should recognize the reality it faces: These capabilities are real, and it cannot get rid of them without paying a catastrophic price. Can the world live with a nuclear North Korea? Yes, for a time. But not without significant danger.Can the world live with a nuclear North Korea? Yes, for a time. But not without significant danger. Despite the words of H.R. McMaster, President Donald Trump’s national security adviser, North Korea can be deterred — at least at the nuclear level. Kim Jong Un is not suicidal. In fact, the need to survive and preserve his regime seems to be the primary impulse behind North Korea’s nuclear and missile programs. The American nuclear deterrent remains robust, and the addition of a North Korean nuclear capability is not likely to change that dynamic. Both Russia and China have maintained the ability to strike the United States for decades, and nuclear deterrence has held. There is no reason to believe that North Korea would be any different in this regard. Yet the same cannot be said of a potential conventional conflict on the Korean Peninsula. For 64 years, the combined might of the U.S. and South Korean militaries, including the American nuclear umbrella, have prevented a general conflict from breaking out again on the Korean Peninsula. The introduction of a North Korean nuclear weapon fundamentally and dangerously changes this dynamic. If North Korea’s leaders feel safe behind their own nuclear deterrent, they may be emboldened to lash out against their adversaries. Recall the events of 2010, when North Korea first sank a South Korean military ship and then fired artillery at a South Korean island, killing a combined 50 South Koreans. Such dangerous provocations, and worse, may become more common in a world with a North Korean nuclear weapon. A nuclear North Korea may also pose a significant proliferation threat, especially as more drastic economic sanctions take their toll. Other rogue regimes and terrorist organizations could be willing to pay top dollar for North Korean material and know-how. For a regime whose only ideology is survival and isolation, dealing with terrorists and other zealots would pose no ethical problem. These are the primary challenges that living with a nuclear North Korea will pose. Can they be addressed? To a degree, yes. The United States can work with its South Korean and Japanese allies to buttress their military posture in and around the Korean Peninsula in order to strengthen their ability to deter and defend against future North Korean provocations. The United States could also build an international coalition to contain the North Korean proliferation threat, and let it be known that proliferation would come at a terrible price. Yet such efforts will not be sufficient in the long run. The combined dangers of North Korean aggression and proliferation are simply too great to accept into perpetuity. Over time, the United States will have to substantially change the fundamentals of this challenge if it hopes to achieve North Korea’s eventual denuclearization. While this strategy could involve negotiations with North Korea to limit, monitor, and eventually do away with its nuclear capabilities, the United States should pursue a strategy that reinvigorates a preventive attack as a more acceptable option. Building toward prevention will require significant investments by the United States and its allies that enhance defense and deterrence, but more broadly it will require us to reorient our posture toward capabilities that what would be needed for preventive attack — a combination of offensive and defensive capabilities that would be several orders of magnitude beyond what is presently deployed to the Korean Peninsula and the immediate vicinity. It would also require substantially increasing investments in missile defense capabilities and technologies in order to deny North Korea’s ability to successfully strike the United States. Such a force would not only give the American president more viable options; it would imbue American negotiators with more leverage when they sit down with North Korean counterparts.