North Korea has test-fired a ballistic missile, which landed 250km off Japan's coast.
Japanese Prime Minister Shinzo Abe condemned it as an outrageous act that posed a serious threat that cannot be tolerated.
North Korea has carried out a series of missile tests this year in defiance of tough UN sanctions, and vowed to take "physical action" against the planned deployment of a US missile defence system in South Korea, announced this month.
Japan's defence minister Gen Nakatani said the missile landed in the Sea of Japan off the north coast in the country's Exclusive Economic Zone - the first time a North Korean missile has landed in Japan's EEZ since 1998.
It was the first ever North Korean missile to land in Japan's EEZ in the Sea of Japan (East Sea) facing the Korean peninsula.
The North Korean missile in 1998 landed in Japan's EEZ in the Pacific Ocean after having flown over the country's territory.
The US State Department said it was aware of reports that North Korea had fired ballistic missiles and said it strongly condemned the latest launches by the isolated country.
"We remain prepared to work with our allies and partners around the world to respond to further DPRK provocations, as well as to defend ourselves and our allies from any attack or provocation," said Julia Mason, a State Department spokeswoman, referring to North Korea by its official name, the Democratic People's Republic of Korea.
Ms Mason said the launches would only "increase the international community's resolve to counter" North Korea's actions.
Yesterday's test was an apparent show of force against the planned deployment of a US missile defence system and comes ahead of a US-South Korea joint military exercise scheduled for later this month.
Last week, North Korea's newly-appointed foreign minister Ri Yong-Ho said any decision to conduct another nuclear test would depend on the behaviour of the United States.
His comments came after US Secretary of State John Kerry warned the North of "real consequences" if it continues nuclear and missile tests in defiance of UN sanctions.
The test follows the launch of three ballistic missiles on 19 July in what the North said were simulated nuclear strikes on the South.
Meanwhile, the United States, Japan and ten other countries have requested a UN investigation of North Korea's ballistic missile tests in a move that could lead to targeted sanctions, according to a joint letter obtained by AFP on Wednesday.
Ten Security Council members along with Australia and South Korea asked the UN sanctions committee to "review carefully the known details" about the 18 July launch of three Scud ballistic missiles and a No Dong intermediate-range missile.
The investigation could identify individuals and companies involved in North Korea's missile program who could face targeted sanctions including a global visa ban and assets freeze.
"As the DPRK proceeds to develop new and destabilizing weapon systems, the Security Council should be prepared to respond with further significant measures," said the letter sent to the sanctions committee on 28 July.
The sanctions committee is asked to "take appropriate action" in response to the launch of the missiles which are in violation of Security Council resolutions.
Aside from the United States and Japan, the request was endorsed by council members Britain, France, Malaysia, New Zealand, Senegal, Spain, Ukraine and Uruguay.
China, North Korea's sole ally, and Russia did not back the request.
