North Korea fired a ballistic missile towards the sea off its east coast on Sunday, ahead of planned military drills by South Korean and US forces involving an aircraft carrier and a visit to the region by US Vice President Kamala Harris, Reuters reported.

South Korea's military said it was a single, short-range ballistic missile fired from near the Taechon area of North Pyongan Province just before 7 a.m. local time and flew about 600 km (373 miles) at an altitude of 60 km and a speed of Mach 5.

Japan's Defense Minister Yasukazu Hamada said Japan estimated the missile reached maximum altitude at 50 km and may have flown on an irregular trajectory. Hamada said it fell outside Japan's exclusive economic zone and there were no reports of problems with shipping or air traffic.

South Korea's Yonhap news agency reported on Saturday that North Korea may also be preparing to test a submarine-launched ballistic missile (SLBM), citing the South's military.