The episode might heighten tension in the area.

South Korea's National Security Council (NSC) held an emergency vice-ministerial meeting over the four shots that fell into the western waters during a span of an hour from 7:20 a.m. from an unspecified location in South Pyongan Province, according to officials as quoted by Yonhap News Agency.

Park Kyung-mee, presidential office spokesperson, told the South Korea news agency that the NSC meeting members stressed the need to maintain "a firm defense readiness posture" based on the South Korean military's enhanced capability and the South Korea-U.S. alliance during a time of a government power transfer.

"There were shots believed to be that of North Korea's multiple rocket launchers this morning," an official of the South Korean military said.