Police help screen passengers at Sydney Airport on July 30, 2017.
Australia has foiled an Islamist-inspired "terrorist plot" to bring down an airplane with an improvised explosive, authorities said on July 30, after four people were arrested in raids across Sydney. / AFP PHOTO / WILLIAM WEST
Police help screen passengers at Sydney Airport on July 30. Australia foiled an ISIL-inspired terror plot on an Etihad flight. William West / AFP Photo

Foiled Sydney plot raises questions about how easily bomb was transported to Australia