South Korea on Sunday resumed anti-North Korean propaganda loudspeaker broadcasts in border areas in retaliation for the North sending over 1,000 balloons filled with trash and manure over the last couple of weeks.

The move is certain to anger Pyongyang and could trigger retaliatory military steps as tensions between the war-divided rivals rise while negotiations over the North’s nuclear ambitions remain stalemated.

South Korea’s Joint Chiefs of Staff confirmed that the military conducted a loudspeaker broadcast Sunday afternoon. It didn’t specify the border area where it took place or what was played over the speakers.