South Korea's acting President Hwang Kyo-ahn condemned the launches as a direct challenge to the global community and said Seoul would deploy a United States anti-missile defence system despite objections from China.
They came as the US and South Korea continued with lengthy joint military exercises, dubbed Foal Eagle.
North Korea's missile launch also coincided with US and South Korean military's annual exercise.
North Korea fired four ballistic missiles that landed in the sea off Japan, the US Pentagon has confirmed. "Having seen the brutality of North Korea from Kim Jong Nam, I'd say the consequences of the Kim Jong Un regime having nuclear weapons will be awful", he said, referring to the assassination of North Korean leader Kim Jong Un's exiled half brother in Malaysia in February.
The station in Tongchang-ri, North Pyongan Province, has been the site of previously long-range rocket tests.
German 'deep state' working against vote, claims Turkish minister
But the German decisions come against the backdrop of renewed strains in relations between Ankara and Berlin over Yucel's arrest.
The US State Department said it remained "prepared to use the full range of capabilities at our disposal against this growing threat". It was not immediately determined what type of missiles were fired Monday.
The previously cordial relationship between Malaysia and North Korea soured following the assassination of Kim Jong-nam, the estranged half-brother of North Korean leader Kim Jong-Un, at the Kuala Lumpur International Airport 2 on Feb 13.
"South Korea and the United States are conducting a close-up analysis, regarding further information", South Korea's Office of Joint Chiefs of Staff added in a statement.
On Friday, Pyongyang threatened to fire missiles in response under way between the USA as well as South Korea.
Kremlin spokesman Dmitry Peskov said Moscow is seriously anxious about the missile drills.
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Caterpillar has defended its tax strategy, calling its practices prudent, lawful and typical among large US companies. The stock, one of the 30 components of the Dow Jones Industrial Average, closed almost 4.3% lower at $94.36 a share.
The incident marked just the second time that North Korean missiles have landed in Japan's EEZ - a 200-nautical mile area off its coast that gives it certain rights in terms of exploitation of natural resources.
The New York Times reported last week that options on the table for Trump to consider range from pre-emptive military strikes to restoring USA tactical nuclear weapons in South Korea. In that case, detecting signs of missile attacks becomes more hard because the North will have a shorter time to prepare a launch.
In a letter to the United Nations security council on Monday, North Korea's ambassador Ja Song Nam claimed the joint exercises that began on 1 March were "the most undisguised nuclear war manoeuvres".
"Since this year's joint drills will be the "largest-ever", North Korea could carry out the "largest-ever" protest against it, including an ICBM launch or a nuclear test", he said.
This year's exercises, which kicked off Wednesday and are scheduled to run until the end of April, are the largest in size, with the nuclear-powered US aircraft carrier Carl Vinson planned to be deployed to waters around South Korea in mid-March.
Chance The Rapper's meeting with Governor Rauner was disappointing, naturally
I have power in some ways; you have great power in other ways. "I'm here because I just want people to do their jobs". His message to the IL governor: " Take our kids off the table " in the state's partisan budget battle.