Seoul, South Korea - South Korean President Lee Jae Myung expressed regret to Pyongyang Monday over drones sent into North Korea earlier this year, actions he called "irresponsible."

Seoul initially denied any official role in the January drone incursion – with authorities suggesting it was the work of civilians – but Lee said a probe had revealed government officials had been involved.

The North warned in February of a "terrible response" if it detects more drones crossing the border from the South, prompting Seoul to investigate the claims.

Pyongyang said it downed a drone carrying "surveillance equipment" in early January.

Photos released by state media showed the wreckage of a winged craft scattered across the ground alongside gray and blue components that allegedly included cameras.

"It has been confirmed that a National Intelligence Service official and an active-duty soldier were involved," Lee told a cabinet meeting.

"We express regret to the North over the unnecessary military tensions caused by the irresponsible and reckless actions of some individuals."

He added that South Korea's constitution bans private individuals from conducting acts that could "provoke the North."

"Such actions, even when deemed necessary for national strategy, must be approached with extreme caution," Lee said.

Lee has sought to repair ties with North Korea since taking office last year, criticizing his predecessor for allegedly sending drones to scatter propaganda over Pyongyang.

His repeated overtures, however, have gone unanswered by the North.

Yoon was impeached and ousted from office in April last year and has been sentenced to life in prison over his declaration of martial law.

Lee's expression of regret follows North Korean leader Kim Jong Un labeling Seoul as the "most hostile state" in a policy address in March, in which he vowed to "thoroughly reject and disregard it."

Kim also reaffirmed his commitment to maintaining the country's nuclear arsenal, describing it as an "irreversible course."

During Yoon's presidency, relations between Seoul and Pyongyang hit rock bottom, with the North sending balloons filled with garbage, including animal manure, in response to propaganda leaflets send northward by South Korea-based activists, many of them North Korean defectors.

The two Koreas technically remain at war, as the 1950-53 conflict ended in an armistice rather than a peace treaty, and both enforce mandatory military service for men.