North Korea's missile launch on Tuesday was a prelude to more military operations directed at the US territory of Guam, North Korean state media said Wednesday.
Pyongyang said it fired an intermediate-range missile Hwasong-12 in Tuesday's test.
The missile's flight path took it over Japan, further fueling tensions between North Korea and the United States and its allies, Japan and South Korea.
Tuesday's launch was "the first step of the military operation of the (North Korean military) in the Pacific and a meaningful prelude to containing Guam," a report from the state-run Korean Central News Agency said.
It said Pyongyang would be "conducting more ballistic rocket launching drills with the Pacific as a target in the future."
'All options on the table'
Earlier, US President Donald Trump warned Pyongyang that "all options are on the table."
Kim Jong Un's regime regularly fires missiles into the sea between its own territory and Japan, however this is the first North Korean ballistic missile to ever fly over the country.
North Korean officials told CNN in Pyongyang the launch was overseen by Kim, who was "very satisfied with the performance of the missile."
They said the launch sent a strong message in response to ongoing joint US-South Korean military drills in the southern half of the Korean Peninsula. State media also pointed out that the launch came on the 107th anniversary of the annexation of Korea by Japan in 1907.
It also followed a fiery exchange of threats and insults between Trump and the North Korean regime in recent weeks, after state media said Kim was considering plans finalized by military chiefs to fire a missile off Guam.
In measured statements Tuesday, Trump said: "The world has received North Korea's latest message loud and clear: this regime has signaled its contempt for its neighbors, for all members of the United Nations, and for minimum standards of acceptable international behavior."
"Threatening and destabilizing 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," he said.
Japanese Prime Minister Shinzo Abe -- who had a 40-minute phone call with Trump on Tuesday -- described the launch as a "reckless act."
"This launch of a North Korean missile is an unprecedented serious and grave threat to Japan," Abe said after the call, adding that Trump said "the US stands with Japan 100%."
"I would like to make the utmost effort to protect the lives and assets of the Japanese people under a strong alliance between Japan and US."
The missile, an intermediate range ballistic missile, was fired just before 6 a.m. Japan time (Monday 5 p.m. ET). The launch set off emergency sirens in northern Japan, triggering text messages that warned residents to seek cover.
"The launch occurred in the vicinity of Sunan Air Base, North Korea and flew east ... The ballistic missile overflew the territory of northern Japan before landing in the Pacific Ocean approximately 500 nautical miles east of Japan," a statement from the Pentagon said.
It set off warnings in the northern part of Japan urging people to seek shelter.
It was the fourth missile North Korea fired in four days -- Pyongyang tested three short-range ballistic missiles, one of which failed, from Kangwon province that landed in water off the Korean Peninsula.
South Korea responded by conducting a bombing drill at 9:30 a.m. local time to test its "capability to destroy the North Korean leadership" in cases of emergency, an official with the country's Defense Ministry told CNN.
Guam has been a focal point of North Korea's anger against the US. The Pacific island is the closest US territory to North Korea. It hosts Andersen Air Force base, from which the US has been staging B-1 bomber flights over the Korean Peninsula, often in response to North Korea's missile tests.
In early August North Korea said it was "examining the operational plan" to strike areas around Guam with medium-to-long-range strategic ballistic missiles.
Specifically, a KCNA statement mentioned a potential strike on Andersen Air Force Base designed "to send a serious warning signal to the US."
In Wednesday's statement, North Korea called Guam the "advanced base of invasion."