麻豆约拍

The attacks in Brussels targeted the city's main airport and a metro station, in areas with little or no security.

Security officials say such attacks - like those in Paris last year and in London in 2005 - are almost impossible to prevent.

Our transport correspondent, Richard Westcott, considers how security at locations such as airports and train stations can be improved, and what this could mean for travellers.

(Photo: A French soldier patrols the railway station in Strasbourg, following the attacks in Brussels. Credit: AFP)