South Korea’s New President Will Face Deep Divisions and the Trump Administration

If there is one characteristic that defines Lee Jae-myung, South Korea’s new president, it’s that he is a survivor.

He has survived criminal charges, a near-fatal stabbing attack and the martial law enacted by his fiercest enemy, former President Yoon Suk Yeol. Now he is taking on what may be his toughest test yet. He must lead a deeply divided nation through daunting challenges, both at home and abroad.

Mr. Lee, who won South Korea’s presidential election after his opponent conceded early Wednesday, takes office as one of the most powerful presidents that South Korea has elected in recent decades. Much of South Korea’s political power is concentrated in the presidency, and Mr. Lee will also wield considerable control over the National Assembly, where his Democratic Party holds a large majority of seats. ​

But long is the list of problems that Mr. Lee faces.

​The political turmoil set off by Mr. Yoon’s short-lived declaration of martial law and his subsequent impeachment and removal​ has exposed a country deeply fractured between the left and right, between generations and between genders. South Korea is ​facing ​mounting pressure from its sole military ally, the United States, even as the nuclear threat from North Korea grows. President Trump has not only slapped South Korea’s export-driven economy with heavy tariffs but also demanded that it pay more to keep American troops on its soil.

​Mr. Lee warned that the second Trump administration was bringing “the law of the jungle” into international relations. But Mr. Lee, 61, who rose to become a charismatic leader of South Korea’s biggest political party after working in a sweatshop in his teens, said he would also rise to this challenge, with “pragmatic diplomacy centered on the national interest.”