North Korea fires missile into Sea of Japan
South Korea's defence ministry said the missile had flown some 60 kilometres (about 40 miles).
"The military is keeping a close watch over North Korea's provocative moves and maintaining a high defence posture", it said.
The US military said it was a KN-15 medium-range ballistic missile which they had determined posed no threat to America.
"US Pacific Command is fully committed to working closely with our Republic of Korea and Japanese allies to maintain security," the military command in the Indo-Asia-Pacific region said.
US Secretary of State Rex Tillerson confirmed Pyongyang had launched "yet another" intermediate range ballistic missile.
"The United States has spoken enough about North Korea. We have no further comment," he said in a statement.
Japan condemned the launch and said it violated UN Security Council resolutions.
