ULAANBAATAR, Mongolia — President Lee Jae Myung attended the opening ceremony of Mongolia's Naadam Festival as an official guest of honor on Saturday, capping off his three-day state visit with a public display of the growing partnership between the two countries. Lee became the first South Korean president to attend Naadam as an official guest of honor during his state visit — the first by a South Korean leader to Mongolia in 15 years. By concluding his trip not in a conference hall but at Mong