North Korea has reportedly test-fired two short-range missiles into the eastern waters.
According to the BBC, a defence ministry spokesman in Seoul said that the missiles were Scuds with the range of 500km (310 miles).
The country launched the missiles ahead of Chinese President Xi Jinping's visit to South Korea to discuss the North's nuclear weapons program.
The country has often test-fired short-range missiles and rockets in the past and is thought to have sufficient nuclear material for a small number of bombs.
North Korea has earlier been slapped with strict sanctions by the UN over its weapons and nuclear programmes.