SEOUL—Nuclear-armed North Korea conducted what could be its largest missile test since 2017 on Sunday, analysts said, after governments in Japan and South Korea reported a suspected ballistic missile launch. South Korea’s Joint Chiefs of Staff reported that a projectile believed to be a single ballistic missile was launched about 7:52 a.m. local time from North Korea’s Jagang Province toward the ocean off its east coast. Japanese Chief Cabinet Secretary Hirokazu Matsuno told a televised briefing that if the projectile was a standard ballistic missile, it is estimated to have reached an altitude of 2,000 kilometers and flown for 30 minutes to a distance of 800 kilometers. Jagang Province was the site of two launches this month of what North Korea said was a “hypersonic missile,” which could reach high speeds while flying and maneuvering at relatively low altitudes. Analysts said if confirmed, Japan’s estimates could indicate one of the …