The launch was the latest in a series of provocations that have ratcheted up tensions over the nuclear-armed North's weapons ambitions.
The launch, which comes as the US prepares to celebrate the Fourth of July holiday, was the latest in a series of provocations that have ratcheted up tensions over the nuclear-armed North's weapons ambitions.
The "unidentified ballistic missile" was fired from a site near Banghyon in North Phyongan province, the South's military said in a statement, and came down in the East Sea, the Korean name for the Sea of Japan.
The device may have come down in Japan's exclusive economic zone, a spokeswoman for Tokyo's defence ministry told AFP -- waters extending 200 nautical miles from its coast.
Pyongyang has carried out multiple launches since Moon -- who backs engagement with the North but also stresses the need for sanctions -- was elected in May.
At their summit in Washington at the weekend, Trump declared that the US had run out of patience with North Korea over its weapons drive, which includes developing a missile capable of delivering a warhead to the US mainland.
"Together, we are facing the threat of the reckless and brutal regime in North Korea," Trump said. "The nuclear and ballistic missile programs of that regime require a determined response."