North Korea warned on Monday that it has put border artillery and possibly nuclear missile units on high alert in response to an alleged South Korean drone intrusion, threatening to retaliate with military force if more aircraft enter its airspace.

In a series of statements, Pyongyang’s defense ministry accused Seoul of planning to send more drones and repeated earlier threats to attack the South, announcing that its troops are ready to strike pre-set targets.

The North Korean leader’s sister Kim Yo Jong also issued another vitriolic warning late on Sunday demanding that the South Korean government “guarantee” no drones from