The two missile tests in a week complicate plans by South Korea's new President Moon Jae-in to seek ways to reduce tension on the peninsula. Moon took office eleven days ago after winning an election on a platform of a more moderate approach to the North, with which the South is still technically at war since no peace treaty was signed at the end of their 1950-1953 conflict.
South Korea's foreign ministry said the tests were "reckless and irresponsible actions throwing cold water over the hopes and desires of this new government and the international community for denuclearization and peace on the Korean peninsula".
Japanese Prime Minister Shinzo Abe said the latest missile test by the reclusive North was "a snub and a challenge to international efforts for a peaceful resolution".
Abe told reporters after a meeting of Japan's National Security Council that he wanted to raise the issue of North Korean missile launches at the Group of Seven leaders' summit in Italy this month. China had no immediate comment.