The missiles did not pose a threat to North America nor to the US territory of Guam, said the Pacific Command.
Later on Saturday, the South Korean Presidential Blue House said the North may have fired an upgraded 300-mm caliber multiple rocket launcher.
Seoul's Joint Chiefs of Staff said that the projectiles fired from the North's eastern coast flew about 155 miles, though it did not mention any failures.
If true, it would be the first time the country has managed to launch an intercontinental ballistic missile (ICBM), which could potentially have the range to reach the US.More news: Dera chief followers throng Panchkula
The missile launches come as tens of thousands of South Korean and United States troops take part in joint military drills in the South, which Pyongyang views as a highly provocative rehearsal for an invasion of its own territory.
The United States on Tuesday slapped sanctions on 16 Chinese and Russian individuals and companies, accusing them of supporting North Korea's nuclear program and attempting to evade US sanctions.
The presidential office in Seoul said the US and South Korean militaries will proceed with their war games "even more thoroughly" in response to the launch.
"We will continue to work with our interagency partners on a more detailed assessment of this latest launch and we will provide a public update if warranted", command spokesman Cmdr.
South Korea is reportedly contemplating the possibility of building a nuclear-powered submarine in light of Pyongyang's missile and nuclear tests.More news: At Least 10 Arrested After Violence Erupts at Berkeley Protest
Japan and U.S. conducted a joint military excercise two weeks - the largest-scale military drill to be held between the two countries - as tensins continued unabated.
The North's missiles have alarmed Japan since a Taepodong-1 overflew its territory in 1998.
However, the North Korean government then seemed to back off, with reports from the Korean Central News Agency (KCNA) saying that leader Kim Jong-Un had vowed to wait a little longer to watch "the foolish and stupid conduct of the Yankees", and urged Washington to refrain from further escalating the Korean crisis.
"This is the most tense I've ever seen [it]", a North Korean official told Ripley.
Earlier this month, President Donald Trump issued an extraordinary ultimatum to North Korea, warning Pyongyang not to make any more threats against the U.S. or it will "face fire and fury like the world has never seen".More news: Taylor Swift's New Album 'Reputation' Coming Nov. 10