South Korean officials say North Korea fired the missiles throughout the day Saturday, launching them in the morning, early afternoon, and early evening.
The missiles were apparently launched from a facility on North Korea's east coast, and are believed to have flown approximately 400 kilometers each.
The Foreign Ministry in Seoul issued a statement calling the launches a "provocative act" and expressing "deep regret over North Korea's continued acts to escalate tensions in Northeast Asia."
South Korean officials say the launches violate the latest United Nations Security Council Resolution 1874, passed after Pyongyang's nuclear weapons test in May. That measure prohibits the North from launching any ballistic missiles whatsoever.
The test launches coincided with the United States' Independence Day holiday, drawing comparisons to North Korea's test of a long-range missile on the July 4 holiday three years ago. The North's May nuclear test fell on the U.S. Memorial Day holiday.
On Thursday, North Korea fired several short range missiles as talks between North and South Korea concluded without progress. South Korean Defense Department spokesman Won Tae-jae says such launches are aimed at getting the South's attention.
He says when North Korea launches missiles with less than a medium range trajectory, they are mostly against South Korea. He adds, South Korea is constantly monitoring signs of such launches.
North Korea is known to possess hundreds of similar short and medium range missiles capable of striking all of South Korea and most of Japan. Military analysts say a North Korean missile barrage could easily kill hundreds of thousands of people here in the capital, Seoul, within a matter of hours.
A maritime advisory issued by North Korea for boats to steer clear of its eastern waters remains in effect until this Thursday. For that reason, nobody is ruling out the test launch of more missiles in the days to come.