South Korea’s Defence Ministry urged the North to stop acts that are unhelpful to easing tension, saying the tests posed a military threat.
It was not immediately clear if the missiles used ballistic technology which would be a breach of UN Security Council resolutions targeting North Korea’s missile and nuclear weapons programmes.
North Korea launched the missiles from the east coast city of Wonsan with one flying about 430 km and the other 690 km over the sea. They both reached an altitude of 50 km, an official at South Korea’s Defence Ministry said.
Some analysts said the North appears to have retested missiles it fired in May, but two South Korean military officials said the missiles appeared to be a new design.
The launch casts new doubt on efforts to restart denuclearisation talks after Trump and Kim met at the demilitarised zone (DMZ) between the two Koreas at the end of June.
US Secretary of State Mike Pompeo and North Korean Foreign Minister Ri Yong Ho had been expected to meet on the sidelines of a Southeast Asian security forum in Bangkok next week.
But a diplomatic source said on Thursday that Ri had cancelled his trip.
The White House, Pentagon and US State Department did not immediately respond to requests for comment.
South Korea had detected signs prior to the launch and was conducting detailed analysis with the United States, the presidential Blue House said in a statement.
Japanese Prime Minister Shinzo Abe said the test had no immediate impact on Japan’s security, according to Kyodo News.
US National Security Adviser John Bolton, who has taken a hard line towards North Korea, made no mention of the launches in a tweet on Thursday after a visit to South Korea. He said he had “productive meetings” on regional security.
Chinese Foreign Ministry spokeswoman Hua Chunying told a briefing that Beijing had noted the launch, calling for North Korea and the United States to reopen negotiations “as early as possible”.