North Korea test-fired what are believed to have been two short-range ballistic missiles on Friday, the general staff of the South Korean armed forces says.
The launches came after North Korea's Foreign Ministry accused the US of "provocation" for imposing further sanctions on Pyongyang for its weapons programme and threatened Washington with a clear response.
The test was the third carried out by North Korea within 10 days. South Korea's National Security Council expressed its "deep regret" about North Korea's continued missile launches.
The United States Indo-Pacific Command accused North Korea of destabilizing the region through its "illegal weapons programme" and said that it also believed the latest test to have involved ballistic missiles.
South Korean authorities believe the missiles were launched in the north-west of North Korea, close to the Chinese border, and travelled about 430 kilometres over the Sea of Japan.
Citing military officials, South Korean news agency Yonhap reported that the missiles were believed to be fired at a predetermined target on an uninhabited North Korean island.
North Korea last conducted missile tests, with what it claimed to be hypersonic missiles, on January 5, and again on Tuesday. Hypersonic weapons are difficult to intercept because of their high speed and manoeuvrability.