Let Me Get This Straight...

So, these potential highjackers were British born citizens of Pakistani origin roaming around the UK, and the UK and Pakistan are allies of the US. Don't we have as much to fear from people born and raised within our own borders and those of our allies than we do from the axis of evil? Why exactly do we have 150,000 troops in Iraq?

I thought we were fighting them over there so we wouldn't have to fight them over here? I'm so confused...