SEOUL: North Korea fired a barrage of artillery shells into a maritime buffer zone on Monday, Seoul’s military said, the latest in a series of launches by an increasingly belligerent Pyongyang.

About 130 artillery rounds were simultaneously fired at 14:59 pm (0559 GMT) from two separate sites, one on North Korea’s east coast and one on the west coasts, the South’s Joint Chiefs of Staff said in a statement.

Seoul’s military said the barrage was a “clear violation” of the 2018 agreement between the North and South that established the buffer zone in a bid to reduce tensions.

It said none of the shells crossed the Northern Limit Line, the de facto maritime border between the two countries.

The military said it had issued “several warnings” over the barrage, without giving any further details.

“Our military is strengthening its readiness posture in preparation for emergencies while tracking and monitoring related developments under close cooperation between South Korea and the United States,” it added.

At a summit in Pyongyang in 2018, former South Korean president Moon Jae-in and the North’s Kim Jong Un agreed to establish buffer zones along land and sea boundaries in a bid to reduce tensions.