Ukrainian President Volodymyr Zelensky proposed on Monday that European nations should band together to form a joint aerial shield that would counter Russian drones and missiles should they be aimed at Ukraine’s allies.

The suggestion comes one week after unidentified drones were sighted in Danish and Norwegian airspace, causing multiple Scandinavian airports to shut down flights for safety reasons. Ukraine has accused Russia of launching the drones, but the Kremlin has denied any involvement.