After months of political turmoil in South Korea, Lee Jae-myung has won the presidential election by a wide margin. Mr. Lee’s campaign has ridden a wave of anger against former President Yoon Suk Yeol after he tried to impose martial law in December.

Lee Jae-myung will be one of the most powerful presidents in decades in South Korea, but he is taking over during a perilous political atmosphere.

© Jun Michael Park for The New York Times

Facing a complex set of thorny challenges at home and abroad, Lee Jae-myung says he will deal with them with “pragmatism.”

© Jun Michael Park for The New York Times

Some of the same young people who demonstrated after President Yoon Suk Yeol declared martial law said they were disappointed by their choices in Tuesday’s election.

© Chang W. Lee/The New York Times

Both of the main candidates support the alliance with the United States, but the front-runner favors diplomacy with North Korea and China to improve strained relations.

Both of the main candidates support the alliance with the United States, but the front-runner favors diplomacy with North Korea and China to improve strained relations.

© Anthony Wallace/Agence France-Presse — Getty Images