The role of a supervisor in protecting company data.
There is a feeling of entitlement in the Western world that enables employees to use company resources for private purposes.  If can use a pencil, you can use a phone, if you can use a phone, you can use your PC to surf the Net on a break. If you can surf the Net, you can look for a job, and if you can look for a job on company time on a company PC, then the next step is sending proprietary company files (files you consider your “own”) to a private Gmail or FTP account just before you leave the company and take that job.
Although entitlement may be a root cause of trusted insider data theft, I doubt we can change Western culture by playing a game of ain’t it  awful.
A group manager/supervisor or team leader must temper this entitlement with personal example and appropriate use of emphatic and uncompromising demands to protect company assets and prevent information leaks.
However, sometimes, an uncompromising demand to meet company data security policy can turn into intimidation. As my friend Isaac Botbol writes in his newsletter on English Communications Skills for Hispanics in the Workplace –

Although intimidation is a negative motivator, it is still a powerful motivator. It implies that there are dire consequences for not following “orders” or instructions such as: “do what I say, or else.” Many front line Hispanic employees have often heard the clear threat behind the message: “si no te gusta, allí esta la puerta” which means “if you don’t like it, there’s the door.”

Leading through intimidation may be sign of a problem between the supervisor and her manager. In many Israeli companies, there are senior managers who are retired senior officers in the Israeli Army. This may result in a management style based on giving and taking orders. The result may be a supervisor who resents her manager and an employee who doesn’t care anyway (in Hebrew it sounds a lot better –  “Zrikat Zayin”  or זריקת זין
To paraphrase my friend Isaac –

By taking a personal interest in developing the leadership skills of your front line supervisors, you’ll be on your way to creating a win-win situation for protecting company data and preventing data leakage.