North Korea previously said that drones sent from the South had violated its airspace, accusing Seoul of a serious provocation and saying it had shot them down.

South Korean President Lee Jae Myung on Monday (Apr 6) expressed regret to North Korea over a drone incursion that he said was carried out by a South Korean individual without government approval, stressing Seoul’s commitment to preventing future incidents.
“Although it was not our government’s intention, we express our regret to the North over the fact that unnecessary military tensions were caused by the irresponsible and reckless actions of some individuals,” Lee said in a Cabinet meeting.
Lee said an investigation by South Korean authorities found that a National Intelligence Service employee and an active-duty military official were involved in the case, adding that the constitution forbade individual acts of provocation against North Korea.
Pyongyang said in January that drones sent from the South had violated its airspace, accusing Seoul of a serious provocation and saying it had shot them down.
Source : https://www.channelnewsasia.com/singapore/south-north-korea-drone-incursion-lee-jae-myung-6038151