North Korea has fired an unidentified projectile from the east coast region of Wonsan on Monday.
It was the latest in a string of launches as the North seeks to build nuclear-tipped intercontinental ballistic missile (ICBM) that can reach the U.S. mainland.
Kim Jong-Un has sought to ramp up North Korea's nuclear programme under his rule, saying the regime needs atomic weapons to defend itself against the threat of invasion.
Japanese Chief Cabinet Secretary Yoshihide Suga said earlier in the day that Tokyo expresses strong protest to Pyongyang as the missile fell into Japan's exclusive economic zone, nearly 190 miles from Japanese Oki Islands. He said there was no immediate report of damage to planes or vessels in the area.
North Korea test-fired a missile Monday into Japan's maritime economic zone - the latest in a series of provocative launches that have heightened tensions over its nuclear weapons ambitions. "In order to deter North Korea, we will take concrete action with the United States", he said.
"This weapon system, whose operation capability has been thoroughly verified, should be mass-produced to deploy all over the country... so as to completely spoil the enemy's wild dream to command the air, boasting of air supremacy and weapon almighty", said the state-run Korean Central News Agency (KCNA). Despite worldwide sanctions, North Korea's capabilities continue to grow.
Monday's test marked the ninth missile provocation this year alone and the third of its kind since the inauguration of South Korean President Moon Jae-in on May 10, the news agency added.
The Japanese government strongly denounced the North as the missile appears to have landed in waters near its territory.
South Korea and Japan have condemned the launches, but North Korea has said its missile testing is in reaction to threats against it by the South, the United States and Japan. It flew about 400km before falling into the Sea of Japan, Japan's Chief Cabinet Secretary Yoshihide Suga said at a press conference.
This comes as America prepares to test an anti-missile systems Tuesday that will simulate a North Korean strike, including an intercontinental ballistic missile for the first time.
North Korea has now conducted nine missile launches this year - three in just the past three weeks.
In an interview with CBS News that aired Sunday before the latest launch, US Secretary of Defense James Mattis said a war with North Korea would be "catastrophic".
He added: "We can not tolerate North Korea's repeated provocations in defiance of warnings from the global community".