The South Korean military conducted an air defense drill against potential North Korean drone incursions in Seoul and surrounding metropolitan areas on Thursday.

The exercise comes after multiple North Korean drones crossed the inter-Korean border and invaded ROK airspace last December. One flew over the capital and breached a special no-fly-zone for protecting the presidential office in central Seoul.

Thursday’s drill is to “prepare for enemy drone invasions” in the future, the army’s Capital Defense Command told journalists on Wednesday.

The defense ministry has estimatedthat Pyongyang possesses between 300 and 1,000 drones, mostly for reconnaissance, according to a 2020