"A Scud ER (extended range) flew about 60 kilometers before suffering an in-flight failiure and crashing into the Sea of Japan," the official told AFP on condition of anonymity.
US and South Korean officials had previously said the missile was a KN-15 medium-range ballistic missile.
Scud missiles are liquid fueled, whereas the KN-15 use solid fuels, meaning they are more mobile and quicker to launch.
Today's missile launch was from a "fixed site" near Sinpo, the official said.