North Korea's fired three short-range ballistic missiles into the sea off its east coast

A spokesman for the US military said they flew about 250 kilometres.

South Korean President Moon Jae-in says the military is keeping "tight surveillance" over the North.

The US says none of the missiles posed a threat to the US Pacific territory of Guam.

The launches come as tens of thousands of South Korean and US troops take part in joint military drills.