"An elite team of Swedish wizards ... who were good at modifying Muggle technology with magic ... were tasked with getting into every airport in Britain and enchanting the security checkpoint gates with magic-detecting Charms before the Wards went up. That way, if someone passed through one, it would alert a special unit who were able to track the signal, and dispatch a Broom-Mounted Hit Team to board the flight once it left British airspace and arrest the magical before they could get anywhere.