The rogue nation, via its state news agency KCNA, said it had succeeded in launching an intercontinental ballistic missile, something leader Kim Jong Un reportedly had claimed to be close to accomplishing.
ICBMs have a minimum range of around 5,500 kilometers and are capable of carrying nuclear weapons. For its part, South Korea did not rule out the possibility of the missile being an ICBM.
"The initial analysis by South Korean and the U.S. authorities is assuming that today's provocation was of a mid-to-long range missile, but we are not ruling out the possibility of the missile being ICBM class," South Korea's President Moon Jae-In said, according to a press pool report on Tuesday.
"If the missile indeed was an ICBM type, we will seek relevant response," he said, adding that his government would "respond firmly," using "all possible means," which included sanctions and dialogue.
A South Korean military official had earlier confirmed to NBC News that an unidentified ballistic missile was fired toward the East Sea from Banghyun area in Northern Pyong An Province at around 9:40 am (KST) Tuesday morning.
North Korea's KCNA said that the missile was a Hwasong-14, which it described as an "almighty ICBM rocket," launched at a steep trajectory, traveling 930 kilometers and reaching an altitude of 2,082 kilometers, according to a transcript translated by NBC News.
The steep trajectory, common with recent launches by the North, prevents its missiles from reaching nearby countries such as Japan, according to Reuters.
The KCNA transcript said that Kim Jong Un personally observed the launch on-site and "declared glorious success throughout the world."
South Korea's Moon had ordered a National Security Council meeting after the launch, South Korean state news agency Yonhap reported, citing the Blue House — the South Korean equivalent of the White House.
The meeting was to determine the country's defense readiness against further incidents, Yonhap said.
"Our military is maintaining full preparedness against the possibility of North Korea's additional provocation," Army Col. Roh Jae-cheon, a spokesman for South Korea's Joint Chiefs of Staff, said, according to a Yonhap report.
Japan's main government spokesperson said there were no reports of damage to planes and ships in the proximity.
"It flew for approximately 40 minutes and is believed to have landed within Japan's economic exclusive zone," he said in comments translated from Japanese by NBC News.
An exclusive economic zone is defined as a 200-mile band from a country's shoreline in which it has jurisdiction over the use of marine resources.
"Today's ballistic missile launch was an extremely problematic act and at the same time a clear violation of the Security Council resolution. We cannot condone these repeated acts of provocation from North Korea and we have lodge our fierce complaint to the North Koreans," he said.
Yonhap, citing the South Korean military, reported the missile flew more than 930 kilometers (around 578 miles).
A U.S. military official said the projectile was an intermediate-range ballistic missile, not a longer-range ICBM, but the official said the U.S. couldn't say what type of missile it was.
The U.S. wasn't yet certain if the missile breached Japan's EEZ, the official told NBC News.
The U.S. Pacific Command said it tracked the missile for 37 minutes and that it landed in the Sea of Japan, noting that the North American Aerospace Defense Command determined it didn't pose a threat to North America.
It's unclear how President Donald Trump would react to the possibility that North Korea has successfully fired a missile capable of carrying a nuclear weapon for long distances. Earlier this year, then President-elect Trump had tweeted that "it won't happen."
Japanese Prime Minister Shinzo Abe said he would aim to increase international pressure on North Korea and he would ask China and Russian leaders to play more constructive roles, Reuters reported.
Rajiv Biswas, an Asia-Pacific economist at IHS Markit, said in a note on Tuesday that the U.S. would likely use the G-20 summit in Germany this week to push for stepped up pressure on North Korea.
"A key focus is likely to be on imposing sanctions on additional banks and companies that are considered to be involved in facilitating illicit North Korean financial activity," he said. "Both the U.S. and the United Nations Security Council have also recently increased the number of companies subject to economic and financial sanctions in relation to involvement in North Korea's nuclear weapons program."
Market reaction was tepid. South Korea's Kospi index was trading at around 2,395 before the news, dipping as low as 2,385.33 afterward, but recovered intraday. But by the close of trade, it was down 0.58 percent, or13.96 points, at 2380.52, having given up pre-launch gains.
Japan's stock market also gave up early gains after the launch, with the Nikkei 225 index closing down 0.12 percent, or 23.45 points, at 20032.35.
The South Korean won initially strengthened on the news, with the dollar fetching as little as 1,146.67 won afterward, compared with as much as 1,149.98 won beforehand. The currency cross was trading at 1149.42 at 3:07 p.m. HK/SIN.
Japan's yen, considered a safe-haven play, also initially strengthened on the news, with the dollar/yen pair falling as low as 113.11 from as high as 113.40 beforehand. But while the pair initially recovered, by 3:08 p.m. HK/SIN, the dollar was fetching 112.95 yen.
In the U.S., Trump expressed concern via Twitter.
"North Korea has just launched another missile. Does this guy have anything better to do with his life? Hard to believe that South Korea ... and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all," he said over two Twitter posts.