What Would a US Withdrawal From South Korea Mean for Japan?

On July 17, the Wall Street Journal reported that the U.S. Department of Defense (DOD) had presented the option of reducing the size of the U.S. military presence in South Korea to the White House. This move has been explained as a part of a broader reassessment of the United States’ overseas military presence, an effort initiated by Defense Secretary Mark Esper. But the proposal’s timing – coming as the United States and South Korea remain deadlocked in bilateral negotiations to renew their Special Measures Agreement (SMA), the alliance’s cost-sharing deal– raises the question of whether the DOD also meant to send a message to Seoul that Washington is serious about withdrawing its troops from the Korean Peninsula should the SMA renewal negotiations ultimately fail. 

Japan – another key U.S. ally in the region – is poised to enter negotiations to renew its own bilateral Special Measures Agreement with the United States later this year. More commonly referred as the Host Nation Support (HNS) agreement, the SMA between the U.S. and Japan is set to expire in March 2021. Even though the official negotiations are not anticipated to begin until the fall, preliminary consultations have been underway between the two bureaucracies for the last several months. In that regard,Japan has been watching closely how the U.S.-South Korea negotiations over SMA renewal are proceeding. The initial failure to reach a renewal agreement for the U.S.-South Korea SMA in 2018 – which forced both sides to resort to the temporary measure of renewing the agreement for one year while continuing to negotiate a full five-year renewal – was already an alarming sign for Japan. It was troubling enough for Tokyo that Washington and Seoul failed yet again to conclude an agreement on a full five-year SMA renewal at the end of 2019, with negotiations remaining at stalemate over halfway into 2020. The DOD’s recent move to float the idea of a U.S. withdrawal from South Korea will be taken far more seriously in Tokyo, as it seems to suggest that Japan may face the same predicament if its own renewal negotiation process does not go well.

Of course, the withdrawal of U.S. troops in South Korea is far easier said than done. The 2020 National Defense Authorization Act (NDAA) dictates that the secretary of defense must make a convincing case that reducing U.S. troops on the Korean Peninsula below the current level of 28,500 is indeed in the United States’ national security interest. The 2020 NDAA further obligates the secretary of defense to certify that the DOD has “appropriately consulted with the allies of the United States, including South Korea and Japan, regarding such a reduction.” In other words, contrary to President Donald Trump’s seemingly arbitrary and unilateral announcement of his intention to reduce the U.S. military presence in Germany, the Trump administration has many more legal hurdles to go through to even begin the process of troop withdrawal from South Korea.

Furthermore, with the Trump administration identifying China as a U.S. strategic competitor and as the tension between Washington and Beijing continues to rise on multiple fronts (the most recent being the United States ordering the closure of the Chinese consulate in Houston and the reciprocal closure of the U.S. consulate in Chengdu), there is a much more effective argument that can be made, even to Trump, that reducing the U.S. presence in Japan at this point in time will harm Washington’s security interests in the region. Unlike U.S. forces in South Korea, which have been primarily aimed at deterring North Korea’s aggression on the peninsula, U.S. forces in Japan play a much broader regional role. Japan is the only U.S. ally in the world that the U.S. Navy calls “home” – Yokosuka is the 7th Fleet’s homeport. Similarly, the U.S. Marine Corps bases its III Marine Expeditionary Force in Okinawa, which plays a critical role in building the capabilities of U.S. allies and partners in the Indo-Pacific region through joint training and other engagements. The U.S. Army in Japan dual-hats as a forward element of the 1st Corps. U.S. Air Force bases in Kadena in Okinawa and Misawa in Aomori are both key refueling and launching stations for U.S. strategic bombers, fighters, and surveillance operations in the Indo-Pacific region. In fact, given the regional roles that all U.S. services play out of Japan, the idea of buttressing the status of U.S. forces in Japan by turning it into an operational command, possibly elevating the commander of U.S. forces in Japan to a four-star position, has been periodically raised. In short, it is easier to make a case that pulling out of Japan disadvantages the United States in its strategic competition with China, and thus that the U.S. will benefit by showing greater flexibility in its SMA negotiation with Japan. 

Moreover, Japan pays quite a bit already to sustain the U.S. military presence on Japanese soil. Currently, Japan pays between 75 and 80 percent of the cost associated with stationing U.S. troops in Japan. These costs include the utilities of base facilities, salaries of base employees, certain repairs and improvement of facilities, and costs of relocating trainings conducted by U.S. forces, among other things. In addition, although it’s technically not included in the cost categories covered under the SMA, Japan also pays parts of the cost of U.S. force realignments (the relocation of the U.S. Marines to Guam, for example) and alleviating the grievances of the local communities that host U.S. forces, such as paying for soundproofing the home of their residents. It is because of these long-standing practices that Jim Mattis, Trump’s first secretary of defense, called Japan “a model ally” for cost-sharing and stated that the U.S.-Japan cost-sharing approach would be a “model for other nations to follow” during his first visit to Japan in February 2017. So, from a financial standpoint, a convincing argument can be made that Japan already pays at minimum its fair share of the cost. 

Finally, the timing of the negotiation is somewhat in Japan’s favor. The U.S.-South Korea SMA renewal negotiations are taking place in the lead up to the 2020 presidential election in November. When the two sides failed to renew their SMA for a full five-year term at the end of 2018, instead having to resort to a stop-gap one-year renewal in the beginning of 2019, it pushed the negotiations into a period when Trump, battered politically at home with impeachment proceedings, was actively looking for something to point to as a “great deal.” This made the outcome of the SMA negotiation – which rarely attracts presidential attention under normal circumstances – politically relevant for Trump. The increased presidential focus, in turn, did not leave the DOD much wiggle room in its negotiation stance. Japan has been said to want to wait until after the presidential election to enter a formal negotiation with the United States on SMA negotiations out of the hope that, should the Trump administration be turned into a lame duck before the negotiation starts, it will be easier for both sides to work toward a compromised solution. Even if Trump gets re-elected, Japan remains hopeful that, without more elections in his future, Trump might not have such an urgent need to score political points. 

So Japan does not have to worry just yet. For the time being, though, it will still have to get prepared for the worst-case scenario: being forced to maintain deterrence with a much smaller U.S. military footprint.