North Korea has fired a suspected ballistic missile off its east coast, just hours before South Korean President Moon Jae-in attended a groundbreaking ceremony for a rail line he hopes will connect the divided Korean peninsula.
North Korea's first launch since October underscored leader Kim Jong-un's New Year vow to bolster the military to counter an unstable international situation amid stalled talks with South Korea and the US.
The presumed missile was fired around 8.10am on Wednesday from an inland location, over the east coast and into the sea, South Korea's Joint Chiefs of Staff (JCS) said.
Hours later, Moon visited the South Korean east coast city of Goseong, near the border with the North, where he broke ground for a new rail line that he called "a stepping stone for peace and regional balance" on the peninsula.
In remarks at the ceremony, Moon acknowledged the launch raised concerns of tensions, and called for North Korea to make sincere efforts for dialogue.
"We should not give up the hope for dialogue in order to fundamentally overcome this situation," he said. "If both Koreas work together and build trust, peace would be achieved one day."
The apparent missile launch by the nuclear-armed North highlighted the challenges Moon faces in his push to achieve a diplomatic breakthrough before his five-year term ends in May.
Reconnecting the two Koreas by rail was a central issue in meetings between Kim and Moon in 2018, but those efforts went nowhere as talks aimed at convincing North Korea to surrender its nuclear weapons in exchange for easing international sanctions faltered in 2019.
South Korea's National Security Council convened an emergency meeting, expressing concern the launch "came at a time when internal and external stability is extremely important" and calling on North Korea to return to talks.
Japan's defence minister said the suspected ballistic missile had flown an estimated 500km.
"Since last year, North Korea has repeatedly launched missiles, which is very regrettable," Japanese Prime Minister Fumio Kishida told reporters.
UN Security Council resolutions ban all ballistic missile and nuclear tests by North Korea, and have imposed sanctions over the programs.
In a report last month, the US government's Congressional Research Service concluded North Korea was "continuing to build a nuclear warfighting capability designed to evade regional ballistic missile defences."