A man tries to set fire to plastic explosive in his shoes, so long queues form (in airports) for people to remove their shoes.
Intelligence comes in about liquid / gel / paste explosives, so now those long queues have to abandon any liquids / gels / pastes in bins, near those long queues, inside an airport. Those "potential explosives" are not allowed on a plane, but are allowed to be left for hours (days?) near lots of people in an airport.
A man tries to set fire to plastic explosive in his shoes, so long queues form (in airports) for people to remove their shoes.
Intelligence comes in about liquid / gel / paste explosives, so now those long queues have to abandon any liquids / gels / pastes in bins, near those long queues, inside an airport. Those "potential explosives" are not allowed on a plane, but are allowed to be left for hours (days?) near lots of people in an airport.