Turning a blind eye to history
No country is whiter than white, but if your going to step in and try and resolve issues in a country you need to make sure you have the higher ground in terms of morals and conduct, otherwise the country your in will see you as no better then the issue you have come to resolve. At the moment there is a lot of double standards floating around which is doing nothing to help the images of the countries supposedly stepping in. Some good examples being, the UK was responsible for Saddam taking control of Iraq in the first place, the US is currently a sticking point for the whole Mid-east conflict.
So bearing that in mind, if the US is the world police and only when it suits the Europeans then they are a very corrupt police force.
Believe it or not, London, in particular, was under terrorist threat for a number of years before 9/11, before most of the average americans could actually tell you where Europe was even. Where was the US world police then, oh yeah they were supporting the terrorists that were trying to blow us up, thanks for that.
By the way as a Police force shouldn't you be addressing some African issues, as there's countless pointless deaths happening there at an alarming and saddening rate, but seeing as they have nothing to offer the US administration in it's quest to become an Empire through economic power, there's no point in interferring I suppose.
If history as taught us anything, it's taught the Brits empire building doesn't work and consumes a lot of resources, if we'd have listened to the Dutch we would have ditched our Empire building (which was through a combination of commerce and military, ring any bells yet, history seems to be repeating itself).