Barack Obama, the US president, has been calling the attempted bombing of a US airliner a "screw up" by his country's intelligence services.

As air passengers face delays caused by tougher security checks, there's growing anger in some of the countries singled out for greater scrutiny.

Al Jazeera asks security and Middle East analyst Fares Braizat if the US can really monitor such large numbers of people, particularly the half a million individuals they call "terror suspects".