james mattis swearing in mike pence sot _00001328.jpg
James Mattis sworn in as defense secretary
01:03 - Source: CNN

Editor’s Note: Jeffrey Hornung is the fellow for the Security and Foreign Affairs Program at Sasakawa USA, a US nonprofit institution providing research and analysis of the US-Japan relationship. The views expressed are his own.

Story highlights

Jeffrey Hornung: Japan, South Korea were shaken by statements Donald Trump made while campaigning

Washington's alliances with Seoul and Tokyo will be critical in managing challenges posed by China and North Korea, he says

CNN  — 

The cavalry is coming! Not exactly, but the sentiment of reassurance is the same. This week, US Defense Secretary James Mattis arrives in Asia to visit South Korea and Japan. Two stalwart US allies, policymakers in both capitals have nevertheless been shaken by statements Donald Trump made while campaigning for President. None of these was more dramatic than the suggestion that these allies should pay more for US troops or risk having these forces withdrawn.

Statements like this played to the worst fears in Seoul and Tokyo that the United States might no longer be a committed ally. It is now Mattis’ job to reassure them of US commitments and return the trajectory of alliance relations back to pre-2016 presidential campaign rhetoric.

Jeffrey Hornung

Of course, the Trump administration is still less than two weeks old, and specific policies pertaining to the Asia-Pacific security realm are nonexistent. But Seoul and Tokyo are understandably anxious because the closest thing they have to gauge the White House’s intentions are memories of what was said on the campaign trail. Indeed, even statements such as presumptive Secretary of State Rex Tillerson’s suggestion that he would consider blocking Chinese access to the artificial islands in the South China Sea, and President Trump’s vow that he will not allow North Korea to develop missiles that are capable of striking the United States, raise more questions than answers.

It is therefore up to Mattis to bring a message of reassurance to reaffirm US commitment to the alliances and to US engagement in the region. And he is arguably the best placed to deliver this message, not only because of his illustrious military career, but because at his confirmation hearing he spoke to the two issues troubling South Korea and Japan the most when he stressed the importance of alliances and the importance of the Pacific theater.

The decision for Mattis’ first official travel to target South Korea and Japan reinforces both the notion that the United States prioritizes the Asia-Pacific region and that it considers the security ties it maintains with South Korea and Japan to be important. Meanwhile, reaffirming the importance of robust alliance relationships signals that, despite all the campaign rhetoric by candidate Trump, these crucial alliance relationships might not deviate all that far from the relations we have known heretofore.

Still, setting aside the symbolic messaging, there are significant issues that the new secretary of defense needs to discuss with his counterparts.

Mattis’ first stop will be South Korea. Here, his agenda is simple. Mattis needs to reaffirm the decision to deploy the THAAD anti-ballistic missile system in South Korea. Similarly, the allies will need to reaffirm the alignment of their policies vis-à-vis North Korea’s nuclear and missile threats. Of these, none is more important than Mattis reiterating the US nuclear guarantee. Given the severity of the North Korean threat, it is crucial they hammer out any possible differences that may have arisen since Trump became president.

From Seoul, Mattis will travel to Tokyo, where his agenda will focus on a separate set of alliance issues. As a former Marine, it will be hard for Mattis to avoid a discussion on Okinawa and questions over the value of seeing the current Futenma Replacement Facility through to the end. Assuming both governments still agree this is the case, he should be clear that the US position under President Trump has not changed in regards to Henoko.

More importantly, Mattis needs to explicitly reaffirm that the disputed Senkaku Islands (claimed by both Japan and China) fall under Article 5 of the US-Japan Security Treaty. As the most capable military in the region, with new legislation enabling a broader set of missions, Mattis should also approach Japan about expanding the role of its self-defense forces abroad to provide logistical assistance in noncombat missions.

While helping serve South Korean and Japanese interests, the trip also serves US interests. Chinese activities in the South and East China Seas have been increasing in their audacity for the past few years. Likewise, although on a low boil for almost two decades, North Korea’s ever-increasing missile and nuclear capabilities promise to threaten the US mainland. There is no time to lose on addressing these issues. In this light, it is crucial for Mattis to hear directly from South Korean and Japanese stakeholders on these specific concerns so the United States is on the same page with its allies should they need to quickly respond over the coming weeks as the Trump administration settles in. Getting China and North Korea right is a function of getting right the US alliances with Japan and South Korea.

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    Finally, Mattis should also advocate for further US-Japan-South Korea security cooperation. Seoul and Tokyo have taken significant steps in recent years, the most notable being the signing of the General Security of Military Information Agreement last year. Yet, although “virtual allies” by sharing a common ally, South Korean and Japanese relations remain mired in history, despite a historic agreement on the most contentious comfort women issue by the governments in December 2015. Because the nature of the regional challenges are only expected to get more difficult with time, Mattis should lay down clarity on expectations that the Department of Defense hopes for these two important allies to continue strengthening this crucial trilateral security relationship.

    Stability of the Asia-Pacific region will be a function of how the challenges presented by China and North Korea are handled. In this effort, Washington’s alliances with Seoul and Tokyo will be critical. Having Mattis visit these allies as his first overseas trip sends a powerful message to regional challengers. It may not completely erase all the anxieties felt in both capitals, but at the very least it should moderate some of the more extreme fears of US disengagement.