North Korean leader Kim Jong Un reacts with members of the Korean People's Army in this undated photo released by North Korea's Korean Central News Agency (KCNA) on May 15, 2017.

South Korea's military said on Wednesday a drone found earlier this month on a mountain near the Demilitarized Zone border was confirmed to have been from North Korea and described it as a "grave provocation" that violated the Korean War truce.

The drone crashed while returning to the North and was found equipped with a camera and aerial photographs of a U.S. anti-missile defense system site in a southern region of South Korea, South Korean officials told a briefing.