On April 4th, South Korea’s Constitutional Court affirmed the National Assembly’s impeachment of President Yoon Suk Yeol, removing him from office for his declaration of martial law last December. The unanimous 8-0 ruling on each of five charges was an overwhelming rebuke of Yoon’s justification for martial law as well as numerous conspiracy theories espoused by his supporters. The court’s ruling triggers a special presidential election in early June which is likely to be won by the progressive opposition party.

On December 3, Yoon declared martial law, blaming “anti-state forces” planning to overthrow the government. He declared that all political activities, including meetings of the National Assembly and public demonstrations, were prohibited and all media would be under government control. He deployed the military and police to prevent the National Assembly from voting on the martial law declaration, which is a protected right in the South Korean constitution.

Yoon claimed he imposed martial law to “protect liberal democracy and ensure the safety of the people” against unidentified forces operating covertly within South Korea. But he provided no evidence for his claims. Instead, it became apparent he was reacting to the opposition party’s obstruction of his legislative agenda and repeated impeachments of Yoon and government officials, which he characterized as a “legislative dictatorship” and “anti-state activities plotting rebellion.”

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During the short six-hour time frame of martial law, the National Assembly scaled walls and evaded troops to vote to overrule Yoon’s martial law declaration, leading him to rescind his declaration. The National Assembly voted on December 14 to impeach Yoon.

The Constitutional Court ruled that Yoon’s declaration of martial law and attempt to seize control of the legislature were “grave violations” of the principles of democratic governance and the rule of law as well as an infringement on the fundamental human rights of the country’s citizens. The court soundly rejected Yoon’s depiction that he had done so as a “signal” against the opposition party’s obstructionism.

As the court deliberated, the government mobilized 14,000 policemen, erected barriers, and closed schools and subway stops near the court due to fears of violent responses after the ruling was announced. However, the pro-Yoon supporters responded peaceably and the large street demonstrations eventually dispersed without incident. Yoon apologized for his “shortcomings” and his ruling People Power Party said it “humbly accepts” the court's ruling. Yoon still faces a separate criminal trial for insurrection which began on April 14.

The unanimity of the court ruling may have inhibited conspiracy-fueled responses. Yoon and his supporters had claimed the April 2024 National Assembly election, which gave the opposition the majority in the unicameral legislature, was stolen by Chinese and North Korean covert influence operations.

South Korea remains riven by political polarization, which was exacerbated by the constitutional crisis. Since December, large demonstrations were held by both sides of the political aisle, including attendance by members of the National Assembly. Though unanimous, the Constitutional Court ruling will not bridge the political divide, particularly in the run-up to the presidential election. Presidential candidates are expected to double down on their parties’ positions rather than seek reconciliation amongst the populace.

Despite the political turmoil, it is clear that South Korea’s constitutional system prevailed and that democratization has firmly taken hold in the country. South Korea is still a relatively young democracy with only 40 years of free elections after decades of authoritarian regimes, coups, and violent protests.

South Korea’s leadership vacuum stymied establishing relations with the Trump administration. Though cabinet ministers and the acting defense minister have met with U.S. counterparts, the acting South Korean president had not directly contacted President Trump until after Yoon’s ruling. South Koreans are concerned over the viability of the U.S. extended deterrence guarantee and the dire impact of U.S. tariffs on the national economy.

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The lack of an elected South Korean president for the next two months and likely electoral change in the ruling party will further hamper bilateral relations. Polls show that the opposition Democratic Party of Korea (DPK) is likely to win the presidential election despite its party leader and leading presidential candidate Lee Jae-myung facing multiple indictments, including election law violations and breach of trust.

Progressive parties such as the DPK have historically implemented foreign policies that are conciliatory to North Korea and China, nationalist and antagonist toward Japan, and seeking greater independence from the United States. Such policies would clash with the Trump administration’s emphasis on confronting Beijing’s aggressive actions against Indo-Pacific nations and predatory business practices.

However, if President Trump sought to re-engage with North Korean leader Kim Jong-un, a DPK government would be more supportive than had Yoon remained in office. Yoon implemented a principled policy against Pyongyang that predicated any negotiations on the regime adhering to UN denuclearization resolutions in return for benefits.

Regardless of the election outcome, the new South Korea president should seek to heal the divisions of the electorate as well as quickly establish direct contact with President Trump to align foreign, security, and economic policies. The military alliance and overall bilateral relationship are critical components for achieving U.S. strategic objectives in the Indo-Pacific.