So its illegal to be a spy in the United States without telling the authorities first?
Fair enough
To a degree. No harm coming over here to gather first-hand information on say recreation in Yellowstone, researching institutions for continueing your education, how to cook a mean pot of chillie, or to research ideal acreage to maybe found your own dairy farm. If it's more buisness related then some authorization or head-nods might be needed first but typicaly it's free-reign, IE - representing your own solar company while here to meet with another solar company to discuss trade and maybe swap manufacturing and technical information. Military technology and intelligence though is a definate no-no without some of the highest authority's permission, especialy when dealing with modern offencive and defencive weapon systems.
Not much is known at this time on what information the spies may of compromised or been targeting. My wild and completely unfounded guess when I first heard this news is that it may have to do with aerospace or aircraft carrier technology since Russia recently unveiled a F-22 copycat and has been recently working on a super-aircraft-carrier project of some form. Whenever Russia unveils something that may have a tie or similarity to an American-developed counterpart it seems to me our goverment goes looking for potential leaks in that department.