Copenhagen Airport halted operations on Monday after multiple drones were spotted in the area. The drones came from several different directions, turning their lights on and off, before disappearing after several hours. Around 35 flights were diverted from the airport. A drone incident was reported on the same evening at Oslo Airport in Norway, forcing all traffic to move to one runway. Danish PM Mette Frederiksen noted the incident was "the most serious attack" on Denmark's critical infrastructure so far and was aligned with "other drone incidents, airspace violations, and hacking attacks on European airports." Security concerns in northern Europe have been heightened over a recent spate of Russian sabotage activities, as well as multiple drones and fighter jet incursions into NATO airspace. Separately in Oslo, an explosion went off near the Israeli Embassy. No one was injured and an undetonated hand grenade was recovered in the area. A 13-year-old suspect was arrested.