The Israeli domestic intelligence organization, Shin Bet, sent out a nationwide warning about Facebook, and other social networking sites. It seems that Islamic terrorists, and foreign spies in general, have been using social networking site profiles to identify those who might have access to useful information (classified data, usually). Shin Bet found out about this when they began to receive reports from Israeli military personnel who had been approached by people wanting to discuss military matters, or openly offering cash for information. Shin Bet has found and arrested some Israelis who decided to do a little business with the enemy.
The Internet recruiters can also spot young Arab Israelis, who are often angry at the way relations between Israel and the Palestinians are working out. Some of these Arabs have been recruited to undertake terrorist attacks inside Israel.