Making citizens from a blacklist of countries undergo tougher airports security checks is wrong and won’t help.

The London bombers were British citizens and Spanish nationals were involved in the development of the Madrid train bombings. Blacklisting people from certain countries will encourage terrorist organisations to use more home-grown terrorists, an arguably even bigger threat to national security.

since we have been too "politically correct" to treat nationals of blacklist-able countries with higher levels of scrutiny, terrorist organizations have been able to pass them right under our noses, without having to bother with the added problem of finding recruits from countries such as Britain and Spain, or supplying one of their local recruits with a visa and going through the whole lengthy process of gaining citizenship in another country. 
 
Forcing them to go through these processes does not lead to complete prevention, no one is claiming that. but it is an added barrier and a deterrent. setting recruits up in foreign countries and supplying them with money til they gain citizenship, that costs money and it takes years... the whole time the recruits have to conceal their identity and affiliations. inevitably some of them will come to the attention of authorities and perhaps some attacks will be prevented that way. 
 
finding people in countries such as britain and spain who share terrorist organizations' radical views is not "JUST AS LIKELY." here is political correctness overriding all common sense. go out in the street in London and randomly ask people if they believe it is right to blow up American planes because it is the will of Allah. now do the same thing in Iran. you really expect the exact same results? really?