North Korea has launched an unidentified missile into the waters off the east coast of South Korea, the South Korean military said.

Pyongyang has staged a series of missile test-launches of various range in recent months.

It was not immediately clear what was fired, but the launch comes days after Seoul and Washington started massive joint military drills.

Leader Kim Jong Un is pushing for a nuclear and missile program that can deter what he calls US and South Korean hostility toward the North.

The South's Joint Chief of Staff said in a statement that Monday's launch was made in the Tongchang-ri area in North Pyongan province.

The area is the home of the North's Seohae Satellite Station, where it has conducted prohibited long-range rocket launches in recent years.

The nation is banned by the UN from any tests of missile or nuclear technology.