Japan’s chief cabinet secretary Yoshihide Suga told reporters: “North Korea’s repeated provocations like this are absolutely unacceptable. We lodged a strong protest and condemned it.”
South Korea’s recently-elected President Moon Jae-in has called for an emergency meeting of the country’s security council.
The launch comes a day after US President Donald Trump spoke on the phone separately with Japan’s Prime Minister Shinzo Abe and China’s President Xi Jinping about North Korea.
The leaders reaffirmed their commitment to a denuclearised Korean Peninsula.
Mr Moon also met with Mr Trump last week, with the US leader warning Pyongyang of a “determined response”..