North Korea fired an unspecified missile on Sunday afternoon, according to South Korea’s military, the official South Korean news agency Yonhap reported on its website.

South Korea’s military said that it appeared to be a ballistic missile, the report said.

The projectile was fired from a site around Pukchang in South Pyeongan province, Yonhap reported, citing a statement from South Korea’s Joint Chiefs of Staff (JCS).

The JCS said the missile flew around 500 km (311 miles), Yonhap reported.

A South Korean defense ministry official told NBC News that they were unsure whether the missile was an ICBM or not.

Reuters reported, citing South Korean sources, that the missile was believed to have hit waters off the country’s east coast.

The White House said it is aware of the launch and noted that the system had a “shorter range” than the missiles in North Korea’s previous three tests, Reuters reported.

This is a breaking news story. Please check back for updates.

Follow CNBC International on Twitter and Facebook.