Organizers of the 2018 Winter Olympics in South Korea have plenty to deal with, including the late addition of North Korea as a participant. But it’s not just events on the ground they have to worry about. Security personnel will be looking skyward, as well—for suspicious drones.

As part of safety precautions, drone-catching drones will be on hand to cast nets over any dangerous-looking unmanned aerial vehicles that approach the Olympics grounds in Pyeongchang. One fear is that an unauthorized drone could be used to deliver a bomb to disrupt the proceedings.

Additionally, security teams have been practicing shooting down such UAVs. In one training scenario, a bomb-carrying drone headed for a bus full of athletes.

Even without the Olympics, South Korea has been beefing up its drone expertise. In December it announced a combat unit centered around weaponized drones, to be used for reconnaissance and other missions in a possible conflict with North Korea. The North, for its part, has sent spy drones over the border, some of which have been recovered by the South after breaking down before they could cross back. And a state-run think tank in the South said last March that the North is presumed to have about about 1,000 drones ready for airborne terror attacks, possibly involving chemical or biological weapons.

The participation of North Korean athletes in the games has reduced fears of the North staging such an attack, but the regime of Kim Jong-un is unpredictable and authorities are taking no chances. It’s not just North Korea, of course: Any number of groups or individuals with bad intentions might want to target a big event like the Olympics. In December South Korea deported 17 foreigners in a preemptive anti-terror move, and the Pyeongchang organizers are also worried about South Korean extremists attacking the North Korean delegation.

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