North Korea launched a ballistic missile on Sunday, according to U.S. and South Korean officials.The medium-range rocket was fired from an area near the North Korean county of Pukchang, and flew eastward more than 300 miles, according to The Associated Press citing South Korea's Joint Chiefs of Staff.The official said in a statement that the country's military "is closely monitoring the North Korean military for any further provocation and maintaining readiness to respond."A White House official confirmed the launch, according to a pool report."We are aware that North Korea launched an MRBM," the official said. "This system, last tested in February, has a shorter range than the missiles launched in North Korea's three most recent tests. We refer you to DoD for further information."This is a developing story and will be updated as more information is confirmed. Copyright 2017 NPR. To see more, visit http://www.npr.org/.