North Korea says front-line units ready to strike South Korea if more drones appear POLITICONorth Korea sends warning to South Korea, saying troops ready to strike if more drones appear Fox NewsNorth Korea says border units on standby to shoot amid drones dispute ReutersSister of North Korea’s leader threatens South Korea over drone flights New York Post North Korea accuses South of flying drones over capital, threatens "all means of attack" if it happens again CBS News