Generally-speaking, these non-Israeli Jewish volunteers are asked to engage in legal activities that will not bring them into trouble with the authorities. There are exceptions, however, as for example in the case of Jonathan Pollard, the U.S. Naval intelligence employee who engaged in espionage on behalf of Israel's intelligence agencies and whose exposure by the FBI strained relations between the U.S. and Israel.
Victor Ostrovsky, a former Mossad katsa turned author, wrote extensively about activities of the sayanim, as has Gordon Thomas. According Ostrovsky and Thomas, the sayanim provide assistance of various kinds to Mossad officers operating in foreign countries. This assistance can include facilitating medical care, money, logistics, and even overt intelligence gathering. They can be Judges, Court Clerks, Expert Witnesses, Child Protective Service Workers, Assistant District Attorneys, Police Officers, or anyone with a great degree of power over people's lives, and will do anything at the behest of Mossad case officers (katsa) for the State of Israel against its enemies or those perceived to be unfavorable politically to Israeli policy. ("By Way of Deception", Victor Ostrovsky). Sayanim are supposedly not directly involved in intelligence operations, and are only paid for their expenses.
In his book "By Way of Deception", Ostrovsky describes the following examples of services the sayanim might provide using their citizenship or residency status or occupation:
- The operator of a car rental agency can rent a car without completing the proper paperwork.
- An apartment manager can provide an apartment without raising suspicions.
- A bank owner or manager can assist in obtaining, exchanging, tranfering or laundering money.
- A doctor can operate on a bullet wound without making a report.
- Merchants can provide large quantities of their wares or help establish false business fronts.
- Employees in high technology can provide direct information on civilian and military technology. Ostrovsky uses the French Exocet missile as an example of military technology that was compromised in this manner.
Sayanim must be 100% Jewish. They live abroad, and though they are not Israeli citizens, many are reached through their relatives in Israel.
Ostrovsky claims that for London alone the Mossad has a list of thousands of recruited and willing sayanim.
Gordon Thomas estimates that in the United States and Britain, there are at least 20,000 sayanim who aid Israel's intelligence agencies in a number of ways.
Katsas are in charge of the sayanim, and most active sayanim will be visited by a katsa once every three months or so, which for the katsa usually means between two and four face-to-face meetings a day with sayanim, along with numerous telephone conversations. The system allows the Mossad to work with a skeleton staff. That's why, for example, a CIA station would employ about 100 people, while a comparable Mossad station would need only six or seven.
The existence of this large body of volunteers allows the costs of intelligence gathering to be greatly reduced, and may be one reason why the Mossad operates with fewer case officers than fellow intelligence agencies.