Author: Darcie Draudt, Johns Hopkins University

The Republican and Democratic National Conventions have confirmed that each presidential candidate has very different foreign policy outlooks. At the heart of each platform are different fears, threat perceptions and understandings of the United States’ place in the world — including its commitment to its treaty allies.

Presumptive Democratic candidate Hillary Clinton was instrumental in crafting the ‘Rebalance to Asia’ policy during her tenure as secretary of state. During her campaign she has repeatedly emphasised the need to further deepen the alliance. There are few surprises to expect in alliance policy and practice if she is elected.

But Republican candidate Donald Trump has repeatedly questioned the value of forward deployment in US security strategy and has threatened to pull back from the alliance if South Korea, among other treaty allies of the United States, does not ‘reimburse us much more substantially’. As a result, some analysts in the region are concerned about the effect of a Trump presidency on the 63-year-old alliance come January 2017.

South Korea does, in fact, pay for the US military presence there. Currently, US–South Korea military burden-sharing is under a period of gradual change, with South Korea increasingly taking on more of the cost of hosting US troops; in the last renegotiation South Korean contributions increased 6 per cent. According to the 2014 Special Measures Agreement (SMA), South Korea now pays 50 per cent of non-personnel costs (approximately US$867 million) associated with US basing. This is in addition to South Korea’s own domestic defence spending, which amounts to an US$35 billion or 2.6 per cent of their annual GDP. South Korea also takes care of the costs of foregone rents and tax exemptions.

Deterring potential attacks from North Korea remains the primary rationale for maintaining a robust military alliance, including stationing over 28,000 US troops in South Korea. While it is notoriously difficult to predict the potential for political bargaining with North Korea, Pyongyang is further retreating from dialogue with both the United States and with South Korea. Inter-Korean relations have reached a low point and institutionalised cooperation programs, such as the Kaesong Industrial Complex have closed.

North Korea is far from coming back to the discussion table. Uncertainty over US commitment adds to the very real possibility that Pyongyang is hunkering down for the long run. Pyongyang may find that it is in its interests to continue its nuclear weapons and missile development program while waiting for new, potentially more sympathetic, administrations in the United States and in South Korea. Then, leadership in the United States and the region at large will need to deal with a more sensitive, withdrawn and nuclear-armed North Korea.

The goals of the alliance are expanding commensurate with South Korea’s position in the world and shifting US regional strategy. The alliance arguably means much more than deterring North Korea: like the entire US system of alliances, the US–South Korea alliance has shifted from one based on threat to one based on capabilities, on the regional and global levels. Particularly since the 1990s, as South Korea’s global outlook has focused on its diplomatic aspirations for a more diversified, multidimensional and cooperative role within the region. Since the mid-2000s, South Korea has diversified its international portfolio through niche diplomacy in areas such as green growth and sustainable development.

The US security guarantee provides assurances as North Korea continues to advance its nuclear weapons and missile development. US diplomatic power in the region is seen by many South Koreans as upholding the liberal international order that led to its economic and political success in the second half of the 20th century. For its part, South Korea has sought to increase its out-of-area participation in peacekeeping, anti-piracy and post-conflict stabilisation efforts, largely partnering with UN Peacekeeping Forces or with the United States. At the same time, the rise of China and shifts in the East Asia regional order forebode difficult challenges for the United States, regardless of the leadership in either country.

US law on the subject is ambiguous, but different historical practices can give credence to arguments that legal power to unilaterally terminate a treaty in the United States may either fall to the president alone, the president and Senate, or to the Congress alone. Trump again fuelled worry over US commitment to its alliances in a New York Times interview on the sidelines of the Republican National Convention in which he claimed as president he would not commit US military aid to NATO treaty allies who ‘aren’t paying their bills’ to his satisfaction.

Such a failure to deliver on security commitments to paying treaty allies under threat — including not only South Korea but also to US alliances worldwide — would undermine the basic framework of treaty alliances and corrode confidence in the US as leader or as partner.

Darcie Draudt is a PhD student in Political Science at the Johns Hopkins University, a non-resident James A. Kelly Korean Studies fellow at Pacific Forum CSIS, and director of research at Sino-NK.