U.S. President Donald Trump, who has been hoping to revive the stalled talks with North Korea, played down the launches. The North has been testing missiles despite Trump's June 30 meeting with North Korean leader Kim Jong Un, where they agreed to revive the talks.
South Korea's government said the latest projectiles fired by the North appeared to be new short-range ballistic missiles.
The missiles flew 220 km (135 miles) and reached an altitude of 25 km (15 miles), the Joint Chiefs of Staff (JCS) in Seoul said.
A U.S. official said U.S. intelligence had detected at least one projectile, and possibly more, that did not pose a threat to North America. U.S. officials said initial information indicated they were similar to two other short-range missile tests by Pyongyang since last week.
North Korean state media said Kim oversaw the firing of what it described as a new large-calibre, multiple-launch guided rocket system on Wednesday. He also observed the launch of a short-range ballistic missile last week.
The launches appear to be intended to put pressure on South Korea and the United States to stop planned military exercises later this month and offer other concessions.
Kim's government was not only signalling negotiating demands with the tests, it was assiduously improving military capabilities, said Leif-Eric Easley, an international relations professor at Seoul's Ewha University.
"The aim is not only to increase Pyongyang's ability to coerce its neighbours, another goal is to normalise North Korea's sanctions-violating tests as if they were as legitimate as South Korea's defensive exercises," Easley said.
Trump was asked at the White House before he set off for a campaign trip to Ohio if he thought Kim was testing him and said the launches did not violate the North Korean leader's promises to him.
Trump said they were short-range missiles. "We never made an agreement on that. I have no problem," he said.
While Trump says he never made an agreement on short-range missiles, the 15-member United Nations Security Council unanimously demanded in 2006 that North Korea suspend all activities related to its ballistic missile programme and "re-establish its pre-existing commitments to a moratorium on missile launching".
The U.N. Security Council met behind closed doors in New York on Thursday to discuss the latest missile launches.
Representatives from Britain, France and Germany called on North Korea after the meeting to engage in meaningful talks with the United States and said international sanctions need to be fully enforced until Pyongyang has dismantled its nuclear and ballistic missile programmes.
The Japanese Ministry of Defence said on Friday no immediate impact was seen on Japan's security after North Korea's latest launch.
No ballistic missiles had reached Japan's territory or its exclusive economic zone, it said in a statement.