North Korea has said it had found the remnants of a South Korean military drone and that any further “violation” of its territory would result in a “declaration of war.”

Tensions between the two sides of the peninsula have escalated since May when the North began flying balloons carrying garbage across the border to the South, prompting Seoul to respond by restarting loudspeaker propaganda broadcasts.

This week, North Korea accused South Korea of flying drones over Pyongyang on three occasions this month and threatened to respond with force if it happened again.