" i would imagine that to be the direct opposite of making concerned visitors feel reassured."
You never know, Julian. I've spoken to many tourists who've been frightened out of their wits at the sight of all the armed police on the streets and elsewhere. I certainly wasn't too impressed with it myself, on our first visit.
It's all down to peoples perceptions isn't it? Some imagine that there must be a pressing reason for so many people to be carrying guns, the thought of which makes them feel doubly uneasy. Whereas, I believe that the official line used to be that the sight of so many firearms in the hands of the forces of law and order, would make the tourists feel much safer, because the government was taking their safety seriously.
Seeing as they are all armed (aren't they?) I suppose that they're 'Damned if they do and damned if they don't' (appear, that is) or so it seems.