Why the U.S.-Korea Alliance Will Survive Moon and Trump

The prevailing narrative in the American media regarding newly-elected South Korean president Moon Jae-in’s first meeting with Donald Trump (aside from how to approach the presidential handshake) revolves around expectations that the chemistry between the left-leaning Moon and the conservative Trump will be bad.

These expectations are amplified by the apparent gap in both leaders’ approaches to the rising North Korean threat and China’s attempts to make missile defense a wedge issue for the U.S.-ROK alliance.

But the main challenge that each leader faces--and the one that will ultimately keep them together--is whether either alliance partner can truly afford to go it alone in the face of a rising North Korean threat.

Moon’s choice: alliance or autonomy

For Moon, the challenges stem from the perennial tension in South Korea’s foreign policy between the desire for autonomy and the need for alliance with the United States to ensure its security (something I detail in my forthcoming book "South Korea at the Crossroads"). The rising peninsular threat from North Korea and growing regional tensions among great power neighbors China, the U.S. and Japan are simply too serious for South Korea to risk its security by pursuing autonomy and abandoning the alliance with the United States.

South Korean progressives are advocating for autonomy within the alliance and have urged Moon to convince Trump to let South Korea “take the lead” on North Korea while also encouraging Seoul to gain greater leverage with China by appeasing Beijing’s objections to the installation of a U.S. mid-tier missile defense system in South Korea.

But Moon must also worry that an overly-assertive approach might bring Trump to devalue consultation with South Korean allies just at a time when South Korea is struggling to overcome signs of “Korea passing” in regional relations following South Korea’s political leadership vacuum and impeachment of the former president.

Thus, South Korea faces contradictory and simultaneous fears that Trump will abandon South Korea and that the U.S. will entrap South Korea amidst rising tensions between Washington and Beijing. Because of the devastating consequences that would arise from a conflict with North Korea, it is in South Korea’s interest to maximize its influence and solidarity within the alliance with its security guarantor, the U.S.

Trump’s choice: unilateralism or joint action against North Korea

The Trump administration’s number one international security challenge stems from North Korean efforts to develop the capability to launch a missile that could be used to launch a direct nuclear strike on the United States. The administration has conducted a policy review and is urgently addressing the North Korean threat primarily by stepping up pressure on China and the international community to enforce sanctions.

Any review of available instruments designed to induce a change in direction in North Korea quickly reveals that South Korean cooperation is essential and that the consequences to South Korea of North Korean retaliation to military coercion would be devastating. The costs to the United States of unilateral actions that ultimately risk rather than preserve the security of its allies would be prohibitive unless they are demonstrably essential to homeland defense against an imminent attack.

The massive pressure and engagement strategy adopted by the Trump administration involves an international campaign to make the costs of North Korea’s nuclear program prohibitive and, as Pacific Commander Admiral Harry Harris has testified before Congress last April, “to bring Kim Jong Un to his senses, not to his knees.” Likewise, efforts to secure greater cooperation from Beijing will only work to the extent that China recognizes that the U.S.-ROK alliance is regarded as essential in thwarting North Korean aims.

Common threats and common purpose

Given the shared U.S.-ROK objective of ending this common threat, there is ample ground for the U.S. and South Korea to build common purpose through a stronger alliance that should deflect North Korean challenges while outweighing the South Korean impulse for autonomy or any American impulse for unilateralism.

Both Trump and Moon may dream of alternatives to the alliance, but in choosing to hold an early summit, both men are also admitting that as a practical matter when it comes to North Korea, there is no viable alternative to cooperation through the U.S.-ROK alliance.

This post originally appeared on Forbes.