North Korea has conducted yet another ballistic missile test. At least one was launched early Friday. The North says it is a response to what it calls a "military provocation" by South Korea.

The missile appears to have landed in the Sea of Japan outside Japan's exclusive economic zone. North Korean state-run media say the South's forces carried out artillery exercises near the border for 10 hours. Pyongyang says it responded with "strong military countermeasures." It is rare for the country to issue a military statement immediately after a ballistic missile launch.

Japanese Defense Minister Hamada Yasukazu says Japan has lodged a protest with the North through its embassy in Beijing.

Hamada said, "North Korea's series of launches is absolutely intolerable, and the significant improvement of its missile technology cannot be overlooked. We will continue to work closely with the US and other countries to gather information, and analyze and monitor North Korea's military moves."

Pyongyang has now tested weapons 27 days this year. On Wednesday, it announced it fired two long-range missiles.

The ruling party's newspaper quoted Leader Kim Jong Un as saying his country will continue to expand the operational sphere of its nuclear forces.