As Joe Biden arrives in Seoul on Friday for his first trip to South Korea as U.S. president, he’ll be forced to confront a daunting challenge that his administration has relegated to the policy backburner as it focuses on the bloody war in Ukraine: nuclear-armed North Korea.

Biden begins a five-day trip to Asia — his first to the region since taking office in January 2021 — with a three-day visit to South Korea for talks with new President Yoon Suk-yeol before heading to Tokyo for a bilateral meeting with Prime Minister Fumio Kishida followed by a summit with “Quad” leaders there.

More than a year into his term, Biden will have much to discuss with Yoon when the two meet for summit talks on Saturday. Topics expected to be broached include strengthening the two countries’ alliance in the face of North Korean saber-rattling, Russia’s invasion of Ukraine and its effects on the Indo-Pacific region, China’s growing regional assertiveness and Seoul’s participation in the U.S.-led Indo-Pacific Economic Framework (IPEF).