South Korea fired warning shots at North Korean soldiers that briefly crossed the heavily fortified border earlier this week, Seoul said Saturday after Pyongyang accused it of risking "uncontrollable" tensions.

South Korea's new leader, Lee Jae Myung, has sought warmer ties with the nuclear-armed North and vowed to build "military trust," but Pyongyang has said it has no interest in improving relations with Seoul.

Seoul's military said several North Korean soldiers crossed the border Tuesday while working in the heavily mined Demilitarized Zone (DMZ) separating the two Koreas.