There is a book called Blind Man's Bluff that documents how this started during the cold war by NSA tapping soviet undersea communication cables.

According to the book one of the captured tapping devices is on display in Moscow and on the side it says "Property of the United States Government". No point in hiding it...

http://en.wikipedia.org/wiki/Blind_Man%27s_Bluff:_The_Untold...