At the end of December, Gatwick Airport, the second largest airport in the UK was shut down after a drone was reportedly sighted flying nearby. Flights resumed at the airport three days later, after the British Army reportedly brought in an Israeli-built drone defense system. To protect themselves from future incidents, both Gatwick and Heathrow airports have invested in their own anti-drone systems.

Heathrow and Gatwick confirmed that they’ve spent millions to acquire and install their own “military-grade anti-drone apparatus,” while Scotland’s Edinburgh Airport has also indicated that it’s taking its own precautions with foot patrols and expand some no-fly zones surrounding the facility. While two people were arrested after the incident in December, they were quickly released, and authorities have yet to make further arrests.

Neither airport indicated what technology they’ve fielded, but they’ve indicated that they will provide a “similar level of protection” as what the Army brought with it in December. That system was reportedly manufactured by Israeli defense contractor Rafael, which allows operators to jam a drone’s radio signals and allow it to land safely.

According to the BBC, the British military has since removed its equipment from Gatwick. The incident has sparked a larger conversation about the threat that consumer drones pose to the country’s infrastructure — mere sightings of a drone (which weren’t photographed, and which authorities say might not have existed) was enough to shut down a major transportation hub for several days.