At this time there is a Russian military flight currently crossing Canada taking photos of what ever the Russians want, including government installations and military bases. This is done under the provisions of the international Treaty on Open Skies.
The treaty is designed to enhance mutual understanding and confidence by giving all participants, regardless of size, a direct role in gathering information from other participating states about military forces and activities of concern to them. As such, this agreement promotes openness and transparency of military forces and activities among the members.
Since the US is also a member of this treaty (http://en.wikipedia.org/wiki/Treaty_on_O...
) that also means that each year there is a Russian military flight crisscrossing the US taking aerial photos of what ever the the Russians want under the authority of this treaty. Of course, US officials are also on the flights and the US also has the right for reciprocal flights but I'm still left wondering how the average American feels about this.