President Donald Trump’s repeated tariff threats and delays have forced Japan and South Korea, two Asian allies, to scramble for a response. In a new letter that sets an Aug. 1, 2025, deadline, Trump threatened to impose 25% tariffs on all imports from 14 countries. He warned, “No extensions will be granted.” Trump added, “If, for any reason, you decide to raise your tariffs, then, whatever the number you choose to raise them by, will be added on to the 25% that we charge.”
Reactions have been overwhelmingly negative. Japanese officials expressed shock, frustration, and anger. Prime Minister Shigeru Ishiba called the latest threat “deeply regrettable,” and pledged to protect Japanese economic interests. In South Korea, where a bilateral free trade agreement (FTA) with the United States is still in force, the latest U.S. threats have created some confusion. “I am not sure if the U.S. took into account the fact that Korea’s tariff rate on [the United States] is close to zero,” said South Korean trade minister Yeo Han-koo.
Trump’s tariff policy is also fueling deeper concerns in Tokyo and Seoul about Washington’s reliability. The proposed U.S. tariffs would not only hurt Japan and South Korea directly but also jeopardize the region’s fragile and still-developing free trade architecture. And they signal that the United States may no longer enjoy the qualities that once made it a credible partner: predictability, transparency, and trustworthiness. While Japan and South Korea will seek compromise tariff deals in the coming weeks, both countries may begin to reassess the long-term viability of cooperation with the United States.
Where do the tariffs stand?
To recap, on April 2, the Trump administration marked “Liberation Day,” announcing a sweeping set of new U.S. tariffs. This included a 10% universal tariff on all imported goods to the United States and 25% to 50% sectoral tariffs in critical industries like automotives, steel and aluminum, and semiconductors. The White House also introduced what it called “reciprocal” tariffs on countries it claims have unfairly benefitted from trade with the United States.
These tariffs have created unprecedented challenges for the two longtime Asian allies. Both Japan and South Korea are already feeling the strain from existing U.S. duties on auto and steel exports – core industries in both economies. U.S. tariff threats are especially acute for South Korea, where exports account for more than 40 percent of GDP, compared to around 20 percent in Japan. By May, South Korean and Japanese exports to the United States fell by 8% and 1.7%, respectively – and are projected to drop further. Sluggish domestic consumption in both counties is only amplifying the pressure.
The U.S. ultimatum also comes at a politically sensitive time in both Japan and South Korea. In Japan, Ishiba faces mounting pressure ahead of the July 20 upper house elections, where his ruling coalition risks losing its supermajority. Trump’s push for Japan to import more U.S. agricultural products – especially rice – has become a flashpoint, drawing backlash from Japanese farmers and consumers. In South Korea, corporate leaders are pressing newly elected President Lee Jae-myung to protect and broaden access to key export markets in the U.S. such as autos. Meanwhile, Trump’s hint at yet another defense burden-sharing arrangement continues to raise concerns that Washington will threaten troop withdrawal as a bargaining chip. Seoul is reportedly pushing for a comprehensive deal with the United States, one that addresses trade, investment, and security concerns.
The U.S. tariffs signal a larger problem
Beyond the immediate economic fallout, Trump’s “tariff bomb” has become a symbol of declining U.S. credibility – and shaky commitments in the region. Insights from international relations scholarship point to predictability, transparency, and mutual trust as the foundation of sustained cooperation. The imposition of sudden, unilateral tariffs on long-standing allies like Japan and South Korea sends the opposite signal.
Indeed, a major obstacle in the current trade talks is the fear in Japan and South Korea that any deal with the United States today may be overturned tomorrow. Officials in both countries point to recent concessions – including increased imports of U.S. agricultural and energy products and higher contributions to host U.S. troops – and question how much more they can give. And though both countries have sought to appease Trump, he seems unconvinced. Trump recently accused both countries of cheating, even calling Japan “spoiled.”
These tensions over trade have led to broader issues of trust and confidence. People in both Japan and South Korea increasingly see the United States as more threatening and less reliable. In a June survey, South Koreans ranked U.S.-China competition and trade protectionism as the two greatest threats to South Korea, at 65% and 60%, respectively. In comparison, only 33% cited North Korea’s nuclear arsenal as the top threat. Meanwhile, an earlier poll in Japan found that only 15% of respondents believed the United States under Trump would defend Japan, down sharply from over 40% in the previous year’s survey results. More broadly, the U.S. reputation for being a “force for good” in the world has fallen dramatically, from 71% to 48% in South Korea and from 65% to 45% in Japan. These findings reflect a rapid decline in American soft power, even among its closest allies.
What now?
Both Asian allies have long operated under the assumption of shared values – and a shared interest in keeping the region “free and open.” Under Trump, many are now openly questioning these assumptions. In targeting Japan and South Korea, Heo Yoon at Sogang University notes, “[Trump] is trying to show that there’s no exception when it comes to tariffs, allies or not.” But it is this lack of differentiation, or prioritization, that the allies find most unsettling. As scholar Victor Cha put it, the message is that “the United States is looking out for itself alone.”
For now, neither Japan nor South Korea has much choice but to accommodate Trump’s demands. But both countries will no doubt look to widen their options. In Japan, for instance, Ishiba has adopted unusually strident rhetoric: “We need to make more efforts to become less dependent on the U.S. It would be a problem if we came to regret that they were telling us to do what they say because of that dependence.” In South Korea, Lee has similarly promised “pragmatism” centered on national – not allied – interests. With diminishing trust and confidence in the United States, these alliances may undergo a slow and quiet reset during Trump’s second term.
Eun A Jo is a 2025-2026 Good Authority fellow.
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