Seems to be the same way that other countries get people to turn on their own in espionage. First ask for something small and insignificant, then increase the scale and scope of the item bit by bit until "giving away top secret information" is not really seen as a large step.
> The Unaoil emails don’t show corrupt third-world kleptocracies shaking down helpless Western corporations. They show the opposite: Unaoil, working for Western companies, is seen slowly corrupting foreign officials, starting off with small gifts and shopping sprees and eventually hooking them on major graft.
http://www.huffingtonpost.com.au/entry/unaoil-bribery-scanda...