North Korea fired a suspected ballistic missile towards the sea on Thursday, Japan's government and coastguard said.

South Korean media also cited South Korea's military as saying North Korea fired an unidentified projectile toward the sea on the east of the Korean Peninsula.

Japan's coast guard said the projectile, believed to be a ballistic missile, had already fallen.

The missile appeared to have landed outside Japan's exclusive economic zone in the sea, NHK reported.

The news comes as ongoing military drills by South Korea and the US were cut short to end on Friday after President Donald Trump ordered a substantial reduction in US participation.

North Korea's Kim Yo Jong, sister of leader Kim Jong Un, said on Wednesday the United States' "hostile policy" towards North Korea had not changed, as the drills were still going on.