Clandestine HUMINT asset recruiting, also known as agent cultivation, refers to the recruitment of human agents, commonly known as spies, who work for a foreign government, or within a host country's government or other target of intelligence interest for the gathering of human intelligence. The work of detecting and "doubling" spies who betray their oaths to work on behalf of a foreign intelligence agency is an important part of counterintelligence.

The term spy refers to human agents that are recruited by case officers of a foreign intelligence agency.

Types of agents Acquiring information may not involve collecting secret documents, but something as simple as observing the number and types of ships in a port. Even though such information might be readily visible, the laws of many countries would consider reporting it to a foreign power as espionage. Other asset roles include support functions such as communications, forgery, disguise, etc.

According to Victor Suvorov, a former Soviet military intelligence officer, a Soviet officer may be under diplomatic or nonofficial cover, handling two kinds of agent: basic and supplementary.

Basic agents can be formed into groups with leaders, or report directly to the controller. Basic agents include information providers, perhaps through espionage or expertise about some local subject. Also in the basic group are "executive agents", who will kill or commit sabotage, and recruiting agents. In US practice, recruiting agents are called access agents.

Both operation leaders and the supplementary group must be clandestine in support roles to basic agents. They may be clandestine officers of the FIS, such as Rudolf Abel, recruited in the target country, or recruited in a third country. One of the supplementary functions is communications, which includes clandestine radio transmission, dead drops, couriers, and finding places for secure radio transmissions. Other supplementary functions include people who can "legalise" agents with cover jobs, and specialists that can forge documents or get illicit copies from the actual source. Safe houses, safe mail drops, and safe telephones are other supplementary functions.

Spotting Recruiting process typically begins with "spotting". Spotting is the identification of targets—people—who appear to have access to information, or are attractive for some support role. This individual may be "developed" over a period of time before the approach is made or it could be made "cold". Alternatively, the potential agent may approach the agency; many intelligence assets were not recruited but were "walk-ins" or "write-ins" who offered information to foreign intelligence services. Background research is conducted on the potential agent to identify any ties to a foreign intelligence agency, select the most promising candidates and approach method.

Obvious candidates are staff officers under diplomatic cover, or officers under nonofficial contact, have routine contact. Also possible contacts of access agents, existing agents, or through information that suggests they may be compromised.

Surveillance of targets (e.g., military or other establishments, open source or compromised reference documents) sometimes reveals people with potential access to information, but no clear means of approaching them. With this group, a secondary survey is in order. Headquarters may be able to suggest an approach, perhaps through a third country or through resources not known to the field station.

Recruiting people that may have access to the activities of non-state groups will be much harder, since these groups tend to be much more clandestine, and often operate on a cell system composed of relatives and people who have known one another for years. Access agents may be especially important here, and it may be worth the effort to spot potential access agents.

The deliberate spotting process complements more obvious candidates, but candidates who are also more likely to be compromised by counterintelligence, such as walk-ins and write-ins.

According to Suvorov, the Soviet GRU was not always able to collect enough material, principally from open sources, to understand the candidate's motivations and vulnerabilities. It was GRU doctrine, therefore, to use every meeting to continue to elicit this information. Other intelligence authorities also see eliciting information as a continuing process.

That continued meetings both provide substantive intelligence, as well as knowledge about the asset, are not incompatible with security. Agent handlers still observe all the rules of clandestinity while developing the agent relationship. Knowledge of meetings, and indeed knowledge of the existence of the asset, must be on a strict need-to-know basis.

Persons with access to technology After the selection of a candidate for recruitment, the first stage, tracing and cultivating, commences. Details are collected about the candidate, details which may be obtained through reference, books, telephone directories, the press, and other recruited agents. Further definition of motives which will be used in the actual recruitment of the person are cultivated and weaknesses are exacerbated.

Persons with access to knowledgeable people Especially when the case officer is of a different culture than the one whose people they are targeting, the recruitment process begins not necessarily with a person that has the desired information. Instead, the first recruit may be someone well-connected in the local culture. Such a person may be called a principal agent or an access agent, who may simply arrange introductions, or actually run the operations of subagents. Some agents of this type may be able to help in the pre-recruitment stages of assessment and development, or may only be involved in finding possible assets.

Indeed, an access agent may arrange introductions without being completely witting that the purpose of meeting the target is to find people who will participate in espionage. A well-respected technical professional, or a professor, often will make introductions within their field. Such introductions are perfectly reasonable in non-espionage contexts, such as looking for jobs or people to fill them. The process of personnel recruiting for industry is not completely dissimilar from recruiting spies. Both may use personal networks, and, in industrialized countries, computer-assisted personal "networking" (for example, through websites such as LinkedIn).

Persons in allied intelligence agencies A professional intelligence officer may very well obtain contacts through counterparts in the intelligence services of allied countries. The other service may arrange direct contact and then drop out of the process, or may jointly operate an asset such as the joint U.S.–UK operation with Oleg Penkovsky. The allied officer may not actually provide access to his assets, but will convey information requests and responses. There is the example of a CIA learned from the Malaysian service about an al-Qaeda meeting in Kuala Lumpur, something that would have been impossible for a lone CIA case officer to discover.

Targeting based on intelligence information HUMINT collectors often have analysts in their own organizations with a sophisticated understanding of the people, with specialized knowledge in targeted countries, industries, or other groups. The analyst may or may not know details of the target's personality.

Even when no personal details are available, the recruiter, in an intelligence service, may have additional resources to use before the first contact. OSINT research can find the publications of a professional, but also social interests. With due regard to the risks and resources required, SIGINT can tap phone lines or intercept other communications that will give the recruiter more information about the target.

Prioritizing potential recruitment This step differs from the next one, assessment of potential recruits, in that it is not focused on the recruit himself or herself, the probability of recruitment, etc., but, when there is more than one possible recruit, and a finite amount of case officer time, the discussion here gives criteria to select the most important person to target as an agent.

One analysis by a U.S. clandestine services officer with knowledge of European practices had five priorities (in descending order of importance) that he used between 1957 and 1962. He developed these in the context of being stationed in Europe during the Cold War, with a goal of acquiring HUMINT recruits in the Soviet Union and its satellite nations. His operations were focused on people with the general characteristics: They were involved in an embassy, legation, consulate, trade mission, and news bureau that constituted the "instrumentalities for that economic penetration, political subversion, and espionage that threatened U.S. interests". That focus could be considered one of counter-intelligence as well as espionage. They were outside "their iron curtains for extended periods of time, two to five years", so recruitment could involve a wide range of United States, and possibly allied, intelligence resources. Among this group, the priorities were: The most valuable recruit had regular access to "current political and economic intelligence from the installation in question". Ideally, the asset would be in the highest-priority country and have access to "the minutes of Politburo meetings" or equally critical military, scientific, or other data. In the case of countries that were either subordinate (e.g., the satellites of the former Soviet Union) or client states of another power, officials of the client country, or of the patron country's representatives in the client, may be easier to recruit than officials in the home country. Nearly as important is an agent who will continue the relationship once he returns to his home country, be that the Soviet Union or a satellite. Recruitment is harder to detect with the less intense counterintelligence surveillance of an independent or satellite country. "Installation penetration thus becomes a means of establishing long-range assets in the satellites by recruiting, testing, and training them while they are abroad". In other words, the priority is to recruit a defector in place, continuing to report. "The Satellite diplomat, foreign trade official, journalist, or intelligence officer who has been useful to us abroad will be even more valuable when he goes back home at the end of his tour, not just because he is then inside the target country, but because the intelligence to which he has access in a ministry headquarters has greater scope and depth. The third priority involves offensive counterintelligence/counterespionage: by observation of intelligence activities operated from embassies of country X, a counterintelligence service can deduce characteristic recruiting and agent handling practices for country X. Because these officers and techniques affect many hostile targets in the country of operations, once this information is known, the foreign intelligence service (FIS) agents can be neutralized in a variety of ways, including police action, convincing the asset in the country of operations to stop cooperating with the FIS, or, ideally, "recruiting the hostile intelligence officer in place". The fourth and fifth priorities are considerably less urgent than the first three. The fourth priority is the "defection of senior diplomatic, trade, or intelligence personnel. Defection can obviously yield only those golden eggs already in the nest; it cuts off the continuing intelligence that could be provided by an in-place asset. It may be worthwhile, however, simply to deny a target country the services of an able and experienced officer, and it may produce, in addition to his store of positive intelligence, leads to his former colleagues who are still in place".