North Korea on Monday fired four missiles into the Sea of Japan, according to officials in Seoul and Tokyo, in a move likely to dramatically escalate tensions in the region.
One of the currently-unidentified projectiles could be an intercontinental ballistic missile, said a South Korean military official without providing further details.
If true, the missile launch could prove a pivotal moment.
In January, Pyongyang announced it was able to launch a long-range missile, capable of hitting the US, whenever it chooses.
The country has never proven such capabilities, but the remarks elicited a rebuke from US President Donald Trump.
“North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won’t happen!” Mr Trump tweeted at the time.
At least one of projectiles was launched at about 7:30am local time from the country’s Dongchang-ri long-range missile site. It flew across the country before splashing down in the Sea of Japan.
Pyongyang last week warned it would conduct more missile tests in response to the ongoing Foal Eagle military drills between Seoul and Washington.
“New types of strategic weapons will soar” said a report in the Rodoing Shinmun, the official newspaper of North Korea’s ruling party.
The South Korean government responded by convening a National Security Council session early Monday morning.
Shinzo Abe, the prime minister of Japan, condemned North Korea after officials confirmed three of the missiles landed in Japan’s exclusive economic zone, an area stretching up to 200 nautical miles, or roughly 370km, from a country’s coastline.
“This is clear evidence that North Korea has become a new threat. North Korea has already claimed that this is a new type of a missile, so we are analysing with great interest,” Mr Abe told reporters, adding Tokyo had already strongly protested to Pyongyang.
North Korea is believed to have landed a missile in the same area for the first time in August of last year.