The U.S. has expelled two Iranian security guards for taking photos around New York City. But if the two were really taking photos designed to assist future terrorist attacks, then shouldn't they have been arrested? After all, they can take the photos and the knowledge and hand it to someone else. I would think that diplomatic immunity would not apply to security guards planning terrorism (but perhaps others can enlighten me on this).
Unfortunately, there may be a cynical response: this is about making headlines that suggest that the Administration is deterring terror. Of course, the reality is that the Administration has eroded our moral high ground and armed terrorists with reports and pictures from Abu Ghraib.