（Tung Chieh Tsai, Distinguished Professor, Graduate Institute of International Politics, National Chung Hsing University）
As is well known, isolationism has long been one of the traditions of U.S. foreign policy. This principle was initially established by the founding fathers including George Washington, and the Monroe Doctrine of 1823 is an important representation of this tradition. Strictly speaking, isolationism is actually a rational hedging choice for small and medium-sized countries. It basically aligns with the international status of the United States at the beginning of its founding. The problem is, once a country successfully rises and joins the ranks of great powers, such a policy clearly requires adjustment. This also reflects the shift from President Theodore Roosevelt's "Big Stick Diplomacy" in 1904 to President Woodrow Wilson’s leading the United States into World War I in 1917. It should be noted that the move away from isolationism was not smooth for the US. The refusal to sign the Treaty of Versailles and the Covenant of the League of Nations in 1920, and the isolation tendencies in the entire 1930s are examples of this. Regardless, since joining World War II in 1941, Washington's strategy of projecting global dominance has finally overshadowed isolationism.
Nevertheless, since Donald Trump’s participation in the presidential election in 2016, a wave of new isolationism, under the slogan "America First," has subtly become mainstream in public opinion. Even though there has been a change of administration since 2020, Biden’s foreign policy has not truly shifted, indicating this tendency. Of course, with Trump’s return to the White House in 2024, this idea of prioritizing narrow national interests and regarding international public goods (maintaining world order through alliances) as secondary will undoubtedly dominate U.S. foreign policy for the next four years. Especially, Trump will no longer have the pressure of re-election, allowing him to fully “be himself” and take bold actions.
As a focal point of current US interests, its future policies towards China and East Asia will be closely watched. First, the US-China trade war which started in 2018 will continue to deepen based on a competition in bilateral relations. Second, due to its less interest in providing public goods, US aid to traditional allies will shift from “obligation” to “transaction” nature. For example, Japan and South Korea may continue to share larger defense costs, while Taiwan will gain more opportunities for “military procurement,” given its potential to generate revenue. Third, Trump may once again engage in the North Korean issue, extending his three meetings with Kim Jong-un in 2018-19. In fact, Pyongyang’s active provocations over the past two years may even reflect its intention of betting on Trump, accumulating bargaining chips for future negotiations. Finally, Trump’s “ambiguous” relationship with Russia may rise to the surface, only that the key issues of their interactions remain uncertain.
Overall, the US shifting towards new isolationism may be difficult to reverse and is likely to accelerate with Trump’s re-election. This will undoubtedly set the stage for a “Trump Shock” that could disrupt the world order led by the US and centered on values since the Cold War. This is a source of concern for those closely aligned with Washington. For instance, will the long-standing geopolitical landscape of East Asis, characterized by island chains be completely transformed? What form will US-China competition take, which is primarily based on practical interests rather than value differences (especially as this competition may not necessarily be zero-sum)? Once the US confirms its shift towards “diminished obligations,” how will it adjust its relations with traditional allies? Of course, even if the US truly returns to isolationism, it won’t happen overnight. It will create a duality in Washington’s foreign policy, making “strategic ambiguity” inevitable. How will this ambiguous duality affect East Asian countries’ choices between two powers, especially facing Beijing’s continued expansion? From a certain perspective, Trump's re-election marks the beginning of these challenges, and their development remains to be closely observed.
（Translated to English by Tracy Chou）
