Today in Gaza, the Hamas regime has arrested several foreign nationals (these are usually Arab decent individuals with foreign passports) as spies working for the Israeli, French , UK and US intelligence organizations. As we all know, these people are not going to get any fair trials if they will get trials at all. Usually they are just dragged through the streets and killed in front of everyone including watching children.
The problem that the Hamas faces is that they are right. There are swarms of spies in the Gaza strip but these spies are not the ones that get caught. Some of them are at the highest level of the Hamas ranks. The secret to success is to have thousands of spies and not tell any spy about another; that way if one or even 10 get caught there are plenty of replacements.