When Handshake Deals Meet Social Media Diplomacy

What happens when a $20 billion investment commitment gets trumped by a social media post?

Donald Trump has threatened to unilaterally reverse the Korea-US tariff agreement through a Monday social media announcement, raising tariffs on Korean automobiles, lumber, and pharmaceuticals from 15% back to 25%. The move overturns an agreement concluded last July and reaffirmed by both leaders in November—all without prior diplomatic consultation.

The New Rules of Engagement

Trump claimed Korea's National Assembly failed to complete legal procedures for the bilateral trade deal. But experts widely interpret this as a sudden move aimed at domestic audiences, potentially pressuring Korea to demonstrate visible results in US-bound investment ahead of an expected Supreme Court ruling on reciprocal tariffs.

The irony? Both countries had already agreed to begin $20 billion in annual Korean investment in the US this year. Korea's pending "special law on US investment" serves as the legal foundation for these commitments, making its passage largely a foregone conclusion.

Korean markets briefly wobbled Tuesday, with auto-related shares leading an intraday drop before stabilizing due to the lack of a specific timeline.

Missed Warning Signals

The tariff reversal exposes concerning gaps in Korea-US communication. Prime Minister Kim Min-seok recently visited Washington, meeting Vice President JD Vance and highlighting the establishment of a "hotline" as a diplomatic achievement. Yet did Kim grasp the seriousness of Trump administration dissatisfaction over Korea's agreement implementation?

Two weeks earlier, the US sent Seoul a formal letter urging compliance with nondiscrimination provisions against US Big Tech companies. While not directly addressing the investment law, this letter from the acting US ambassador represented a clear formal expression of grievances—warning signs Seoul should have recognized and addressed proactively.

The Coupang Connection

The timing isn't coincidental. Frictions are emerging across multiple fronts, including the Coupang arbitration case and digital regulation disputes. These interconnected issues suggest a broader pattern of US frustration with Korea's regulatory approach toward American companies.

President Lee Jae-myung advocated a principled approach at his New Year's press conference, stating that "reacting emotionally makes it hard to stay centered" and responses should be "guided by established policies and principles." This measured stance remains valid, yet the latest turmoil demonstrates Korea must prevent a downward spiral of mistrust.

Beyond Traditional Diplomacy

Trump's social media diplomacy represents a fundamental shift from traditional diplomatic channels. For Korea, this creates a new challenge: how to maintain stable relations with an unpredictable partner who bypasses conventional protocols?

The Korean government must now recalibrate its approach, accurately assessing US intentions while responding with carefully calibrated measures grounded in national interest. The National Assembly, too, faces pressure to halt partisan conflicts and actively cooperate—the investment law's passage has become more than domestic politics; it's now a litmus test for alliance credibility.