Celebrations as South Korean Court Removes Impeached President Yoon Suk Yeol

South Korea’s top court ended months of political turmoil when it unanimously decided to remove the impeached president Yoon Suk Yeol on Friday, clearing the way for the country to elect a new leader.

But the political crisis that Mr. Yoon triggered with his misjudged declaration of martial law in December — and his ensuing impeachment by the National Assembly — exposed a deep fissure in South Korea’s polarized politics that may prove harder to heal. For months, protesters for and against Mr. Yoon have taken over the streets in Seoul.

The country must continue without an elected leader before the elections take place, as it deals with external challenges that include the deepening military cooperation between North Korea and Russia and an upheaval in global trade ignited by President Donald J. Trump’s new tariffs.

But after months of political limbo, the ruling by the Constitutional Court on Friday finally gave South Korea a sense of direction that it has desperately needed.

Mr. Yoon, who had defiantly held onto his job despite his impeachment, is a former president now. In the coming days, he must vacate his hilltop presidential residence in central Seoul, and the government will schedule a national election because his successor must be chosen within 60 days. On Friday, officials lowered a presidential emblem in front of a building from where Mr. Yoon used to run the government. Military units began removing his portraits.

“This is a victory for South Korean democracy,” said Sung Deuk Hahm, dean of the Graduate School of Political Studies at Kyonggi University, remembering how South Koreans had sacrificed their lives to oppose military rule in the past. “It has taken time, but this time, the rule of law eventually prevailed without blood-shedding or serious violence.”

Mr. Yoon’s institution of martial law, which lasted six hours until the National Assembly voted to kill it, was the first attempt by a South Korean leader to use the military as a political tool since the country began democratizing in the 1980s.

In a ruling millions of South Koreans, including schoolchildren, watched on live television on Friday, the Constitutional Court found Mr. Yoon guilty of “violating the constitutional order” and “betraying the people’s trust” when he sent troops to seize the legislature during his short-lived martial law.

Hours before the ruling, supporters and opponents of Mr. Yoon gathered for rival rallies in Seoul, some camping out on the pavement overnight. As Acting Chief Justice Moon Hyungbae began reading out the 22-minute-long decision, silence fell as the crowds listened intently to every word of the ruling that would determine Mr. Yoon’s fate — and the future of South Korea’s democracy. Some clasped their hands together in prayer.

When the verdict came, a crowd gathered near the court erupted. Those supporting Mr. Yoon’s removal reacted with screams of delight, pumping their fists into the air and hugging each other.

“This is the day I’ve been waiting for over the past four months of protesting,” said Jang Jaeeuk, 21, who said he had stayed out on the street near the court overnight along with other students from his university, getting only three hours of sleep.

At a rally of supporters of Mr. Yoon, there was loud booing. Some people folded over in dismay, and others loudly cursed.

Ye Chung-ho, 65, had come to Seoul from Geoje Island, off the south coast of South Korea, spending two nights on the street to support Mr. Yoon.

“The constitution has collapsed,” he said after the ruling. “The decision is illegal.”

But the crowds dispersed quickly after the court’s announcement despite earlier fears of violent clashes. The police had been on their highest alert, erecting tall barricades around the courthouse. Schools in the neighborhood were closed. Businesses told employees to work from home.

“Today marks the beginning of a true South Korea,” said Lee Jae-myung, the main opposition leader, who campaigned for Mr. Yoon’s removal. Mr. Lee is expected to win the nomination of the Democratic Party, and polls have shown that he had the strongest chance to win if a presidential election were held now. No strong front-runner has emerged in Mr. Yoon’s party.

Mr. Yoon thanked his supporters and apologized to the people. But he did not comment directly on the court’s ruling, only saying: “I am regretful and sorry that I could not live up to your expectations.”

But his People Power Party said it “humbly” accepted the ruling.

Political turmoil could continue if Mr. Yoon’s hard-line supporters continue their protests. But “it won’t pose a big threat, as the People Power Party must shift its gears toward the new election,” said Ahn Byong-jin, a professor of political science at Kyung Hee University in Seoul.

Mr. Yoon plunged his country into its biggest political crisis in decades when he suddenly declared martial law on Dec. 3 at a time when many world leaders were busy preparing for Mr. Trump’s return to the White House. Instead of building bipartisan cooperation, he attempted to seize the National Assembly with troops, labeling the opposition “anti-state forces.” Citizens quickly mobilized to block the military takeover, giving lawmakers time to gather and vote down his martial law declaration. Mr. Yoon ended up getting impeached, leaving his country to face Mr. Trump — and North Korea’s leader Kim Jong-un — under an acting president with no popular mandate.

“South Korea has managed to avoid the worst outcomes and can see light at the end of a long political crisis,” Leif-Eric Easley, a professor of international studies at Ewha Womans University in Seoul, said about Friday’s ruling. “And not a moment too soon, given how the next administration in Seoul must navigate North Korea’s military threats, China’s diplomatic pressure and Trump’s trade tariffs.”

Mr. Yoon’s ouster was a crushing blow to the country’s conservative camp: He was the second conservative president in a row to be ousted by impeachment. (The first was President Park Geun-hye in 2017). It increased the chances of his progressive foes in the current opposition to regain power and reshape South Korea’s foreign policy.

Mr. Yoon pleased conservatives by adopting tough stances toward North Korea and China and expanding joint military drills with the United States. He also won plaudits from Washington when he improved ties with Japan to lay the ground for trilateral cooperation to deter China. His progressive rivals favor dialogue with North Korea and seek to be on good terms with both the United States, South Korea’s main military ally, and China, its biggest trade partner.

“It will be an uphill battle for the conservative party to win a snap presidential election,” said Duyeon Kim, a Seoul-based fellow with the Center for a New American Security. “If Lee wins, South Korea’s foreign policy will likely look very different from what the U.S. and like-minded countries have enjoyed during Yoon’s presidency, because of the demands of the progressive base.”

Mr. Yoon’s martial law also exposed how dangerously close the county could come to a military takeover. South Korea is grappling with a deepening political polarization, online demagoguery and the mainstreaming of a radical right wing. Its legislature is gridlocked by partisan warfare.

“Whoever wins the next election will face the daunting challenges of bringing together a deeply fractured society, as well as dealing with Trump’s tariffs,” said Mr. Hahm.