North Korea sent hundreds more trash-carrying balloons over the border, Seoul’s military said Monday, after Kim Jong Un’s powerful sister warned of further responses if the South keeps up its “psychological warfare”.

In recent weeks, North Korea has sent hundreds of balloons into the South, carrying trash like cigarette butts and toilet paper, in what it calls retaliation for balloons laden with anti-Pyongyang propaganda floated northwards by activists in the South, which Seoul legally cannot stop.

The South Korean government this month fully suspended a 2018 tension-reducing military deal and restarted loudspeaker propaganda broadcasts along the border in response to Pyongyang’s balloons, infuriating the North which warned Seoul was creating “a new crisis”.