The emergence of the Trump era which has come to be symbolized by a stance of `America First and Peace through Strength` is both a challenge and opportunity for the ROK-U.S. alliance The Trump administration`s Maximum Pressure & Engagement Policy toward North Korea aims at sanctions and eventually dialogue. In the meantime, the ROK`s Moon Jae-in administration is attempting to implement sanctions in parallel with dialogue. Both governments` end-state is to achieve peace-making on the peninsula. In the event of the complete disbandment of nuclear and missile development, our two allies are to reach an agreement of a nuclear freeze and non-proliferation through the Six-Party Talks and eventually sign a peace treaty along with North Korea`s denuclearization. Just after Trump`s inauguration, the solidity of the ROK-U.S. alliance and firm commitment to the defense of the ROK was demonstrated through the subsequent visits to Korea by U.S. Secretaries of Defense and State, and the Vice President. The alliance is a backbone of the ROK`s national security and a core pillar of its foreign existence. The alliance transforms not only the deterrence of war but also contributes to achieving a unified Korea. The alliance should be transformed to a strategic alliance so as to cope with international terrorism, the non-proliferation of WMDs, cyber security, humanitarian assistance and disaster relief. In the meantime, we should be aware of North Korea`s intent and strategy regarding nuclear and missile development due to its regime survival, deterrence, and negotiation. Also of great importance is its stated goal of unification in a military manner of nuclear and through possible missile preemptive attacks. The situation in which North Korea retains fifty nuclear warheads, ICBMs striking against continental U.S, and 3000 ton SLBM is moving beyond control. North Korea should be prevented from waging nuclear war. In the event of identifying clear-cut indicators of a nuclear-missile attack and crossing such a redline, neutralization operations against nuclear and missile sites should be carried out. Military operations systems should be established, strategic communication should be conducted in order to get a ROK-U.S. and international consensus regarding the urgency of the elimination of nuclear and missile armaments, national determination to wage a total war achieved, and be ready to conduct a neutralization strategy against North Korea`s nuclear program under full-fledged deployment in order to prevent the escalation of war. THAAD deployment is essential to protect Korean people and property as well as U.S. troop protection and survival. The procedure of environment impact assessment and national assembly`s agreement will secure- legitimacy. The ROK should proactively respond against China`s criticism related to X-band radar`s detection inland military activities of China and ROK`s Missile Defense System led by the U.S. Conditionally, China should cross-visit the MD system in the Northeast Province and the THAAD site in Sungjoo in order to confirm the issue of compatibility between AN/TPY-2 Terminal Mode Radar (range of detection, 800 Km) and Forward Based Mode Radar (range of detection, 1,800 Km). The compatibility between the two radars is absolutely impossible. The worst option might also be reviewed. All THAAD systems should be deployed at the Sungjoo site along with operational personnel, except the radar which might be redeployed to an off-peninsula location. The radar during annual exercises, such as the Key-Resolve Exercise, will be deployed to the Sungjoo site to test the interoperability with the THAAD system. The radar will be returned to an alternate site off-peninsula. In the event of identifying clear-cut indicator of high tension on the peninsula, the radar will be promptly deployed to the Sungjoo site. However, the option has intrinsic constraints because the deployment of THAAD is played as a denial deterrence role. The proof of which the ROK has not joined the MD system led by the U.S. is as follows. First, the ROK did not sign an MOU on the MD with the U.S. Second, the ROK has never invested toward research and development related to MD weapons systems. Third, the ROK forces did not connect with the Command and Control, Battle Management Center. The ROK has also maintained its non-member status of MD systems since the Kim Dae-jung era. President Moon Jae-in should proclaim again that the ROK is not joining, and will never join, MD systems. It is highly-likely that the Trump administration will request a drastic rise of the defense burden sharing under consideration of THAAD deployment expenditure request by President Trump. The ROK`s defense burden as of 2016 is roughly 50% - 944 billion won among the two trillion won it costs to host US forces in South Korea. In terms of burden sharing ratio toward GDP, South Korea is the highest: South Korea 0.068%, Japan 0.064%, and Germany 0.016%. The ROK is the largest purchasing country in the world with 36 trillion three-six million won acquisition of U.S. weapons in the past 10 years from 2006 to 2015. Unlike Japan, the land cost for U.S. camps and personnel expenditure for 3,000 Korean Augmentation forces to U.S. Army KATUSA are excluded. The ROK government invested eight trillion 900 billion won, which is more than half of U.S. forces relocation expenditure. All those items, including the expenditure of Sungjoo THAAD site, should be included in order to account for the defense burden. A negotiation strategy is required so that the ratio of defense burden could be raised to more than 75% which is equivalent to one trillion 300-400 billion won. Then, the ROK could insure the presence of strategic assets via rotation deployment and joint employment. Finally, no personnel from the Trump administration has mentioned the transition of wartime operational control(OPCON). It is said of critically that mere discussion of the transition of wartime operations is not appropriate in considering the nuclear crisis. However, considering Trump`s speech emphasizing the responsibility delivered at HQs NATO in May 23, 2017, it looks highly likely that he will address the transition of wartime control. Even though the ROK-U.S. pursues condition-based transitions of OPCON, the judgment and assessment criteria are ambiguous. As long as the North Korean threat remains and the security environment is unlikely to improve, the transition of OPCON will never be implemented. Even though the ROK has spent an overwhelmingly larger amount on its defense budget versus that of North Korea in the past several decades, why does the ROK defend itself relying on a heavy dependence on the U.S. The need for the transition of OPCON is primary to recover the autonomy of the ROK`s military power`s employment. Once transition of OPCON is implemented, then the ROK could take the initiative of unification. In the event of war, the ROK will take the lead in military operations which could prevent China`s PLA intervention. Arms control military talks between the two Koreas could be held. As long as OPCON will be retained by the CFC commander, North Korea will talk only to the U.S. excluding the South. Autonomy will also contribute to expanding the diplomatic landscape. Preparation for the transition of wartime OPCON which fundamentally transforms the national security frame should be handled by the national forces` commander-in-chief himself. It cannot delegate authority to military forces. National level`s transition preparation of transition of wartime OPCON should be made. The president of South Korea should host quarterly conferences for reviewing the transition preparation of wartime OPCON. Areas of confirmation are as follows. ① Encourage a national campaign to enhance the Korean people`s sense of self-reliant national defense ② The function of the NSC should be reinforced, and war guidance systems should be established ③ In order to cope with North Korea`s nuclear challenge, a task force dedicated to nuclear operations should be organized at the Blue House, and early modernization of the three pillars consisting of a Kill-chain, Korea Air Missile Defense system and Korea Massive Retaliation and Punishment, and activation of strategic command ④ The CFC should relocate to the Combat Lab Center building of ROK JCS in order to hand over how to wage war, then readjust the ROK-U.S. command structure from which the future command might be a commander from Chairman, ROK Chiefs of Staff(CJCS) and deputy commander of Future Command by USFK Commander. ⑤ Restructure of the higher echelons by exercising CJCS`s unitary commandership over sister service chiefs of staff under his command ⑥ Enhancement of warfighting capabilities, including strategic intelligence assessment, military strategy, operation planning and command leadership for joint-combined operations, ⑦ Self-reliant defense capabilities by gradually increasing the defense budget from 2.4% to 3% versus GNP. ⑧ Rebuilding USFK`s status and developing a strategic alliance to cope with the regional and global security agenda. ⑨ Parallel talks for North Korea`s denuclearization, peace forum, and arms reduction. ⑩ Improvement of the security environment by institutionalizing peaceful cooperation in Northeast Asia through a backbone of the Trilateral Cooperation Secretariat in Seoul since 2011. Then the ROK will implement the transition of wartime operational control within the ROK`s new administration. The emergence of the Trump era, which symbolizes the transformation of alliance based on reciprocity of responsibility and roles requires renewing ROK-U.S. military relations. We should resolve the North Korean nuclear issue and retain national interest through a solid ROK-U.S. alliance and self-reliant foreign and security capabilities When the ROK-U.S. alliance, which has already contributed to industrialization and democratization through the deterrence of war on the peninsula enables the ROK to achieve a self-reliant defense, the alliance will be a great model for future alliances in the global community.