North Korea says it conducted a test of an intermediate-range ballistic missile over Japan as the first step in military action in the Pacific to "contain" the US territory of Guam.
The North's leader Kim Jong-un ordered the missile drill to be conducted for the first time from its capital, Pyongyang, to counter US and South Korean military drills.
Mr Kim told the North's KCNA news agency that it was necessary to undertake more exercises with the Pacific as the target.
"The current ballistic rocket launching drill like a real war is the first step of the military operation of the KPA in the Pacific and a meaningful prelude to containing Guam," KCNA quoted Mr Kim as saying.
The Korean People's Army (KPA) is the North's military.
Earlier this month, North Korea threatened to fire four missiles into the sea near Guam, home to a major military presence, after US President Donald Trump said the North would face "fire and fury" if it threatened the United States.
Tuesday's test was of the same Hwasong-12 missile Mr Kim had threatened to use on Guam, but the test flight took it another direction, over northern Japan's Hokkaido and into the North Pacific Ocean.
Mr Trump, who has vowed not to let North Korea develop nuclear missiles that can hit the mainland United States, said the world had received North Korea's latest message "loud and clear".
"Threatening and destabilising actions only increase the North Korean regime's isolation in the region and among all nations of the world. All options are on the table," Mr Trump said in a statement.
The launch came as US and South Korean forces conducted annual military exercises on the Korean peninsula, angering Pyongyang which sees the war games as a preparation for invasion.
North Korea has conducted dozens of ballistic missile tests under Kim in defiance of UN sanctions, but firing a projectile over mainland Japan was a rare and provocative move.
Reports of the launch by North Korean media were lacking the usual boasts of technical advances, indicating the test may not have accomplished its intended technical goals.
The 2700km the missile flew before splashing down was much shorter and at a lower trajectory than that of an earlier and lofted launch of the same missile.
The May launch would have had a range of about 4800 km on a standard trajectory, an expert on missile technology, David Wright of the Union of Concerned Scientists said.
Japan reacted sharply to the missile overflight, warnings residents to take cover as the missile approached and raising protests at the United Nations.
The United States has said before that all options, including military, are on the table, although its preference is for a diplomatic solution.
US Ambassador to the United Nations Nikki Haley said the launch was "absolutely unacceptable and irresponsible" and that the Security Council now needed to take serious action.
The Security Council earlier this month unanimously imposed new sanctions on North Korea after it staged two long-range missile launches in July.
South Korea and the United States have discussed deploying additional "strategic assets" on the Korean peninsula, South Korea's presidential Blue House said in a statement, without giving more details.