It is the sixth round of weapons launches since late July.
North Korean leader Kim Jong Un oversaw the test-firing of a new weapon again on Friday morning, state media KCNA said on Saturday.
North Korea launched at least two short-range ballistic missiles on Friday, South Korea's military said, its sixth round of weapons launches since late July, complicating efforts to restart talks between the United States and North Korea over Pyongyang's weapons programmes.
Stephen Biegun, the US special envoy for North Korea will travel to Japan and South Korea next week to coordinate efforts to secure the denuclearization of North Korea, the State Department said on Friday.
News of Biegun's trip came after US President Donald Trump said last Saturday that Kim had told him he was ready to resume stalled denuclearization talks with the United States and would stop recent missile testing as soon as US-South Korea military exercises that have been held this month end.
The North has protested against joint US-South Korea military drills, which kicked off last week, calling them a rehearsal for war.
An official at Seoul's defense ministry said on Friday that there was a possibility that the North fired the same type of missiles it used on August 10, which Pyongyang also called "a new weapon" at that time.
Last week, Trump played down the North's recent missile tests, saying they do not violate Kim's pledge to forego nuclear and long-range tests. Trump also said that he had just received a "very beautiful letter' from Kim and added that he could have another meeting with him.
The denuclearization talks have been in a stalemate since a June 30 meeting between the two leaders.
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