Editing Surveillance (section)

===Human operatives===
A [[tailing (disambiguation)| tail]] may surreptitiously track and report on the movements and contacts of a person of interest. Such following by one or more people may provide useful in formation in relatively densely populated urban environments.<ref>
{{cite book
 |last1                = Prunckun
 |first1               = Hank
 |orig-date            = 2010
 |chapter              = Clandestine and Covert Sources of Information
 |title                = Methods of Inquiry for Intelligence Analysis
 |url                  = https://books.google.com/books?id=mqSNDwAAQBAJ
 |series               = Security and Professional Intelligence Education Series
 |date = April 12, 2019
 |edition              = 3
 |publication-place    = Lanham, Maryland
 |publisher            = Rowman & Littlefield
 |publication-date     = 2019
 |page                 = 57
 |isbn                 = 9781538125885
 |access-date          = 13 September 2022
 |quote                = Physical surveillance is the act of making observations of people, vehicles, or the activities occurring at specific locations. [...] Physical surveillance may take place either at a fixed location, which is known as a stakeout, or in a continually moving situation, referred to as a tail.
}} 
</ref>

Organizations that have enemies who wish to gather information about the groups' members or activities face the issue of potential infiltration.<ref name="pentagon-infiltration">{{cite news|url= https://www.nbcnews.com/id/wbna10454316 |title= Is the Pentagon spying on Americans?|last= Myers|first= Lisa|date= December 14, 2005|work=NBC Nightly News|publisher=NBC News|access-date=March 13, 2009}}</ref>

In addition to operatives' infiltrating an organization, the surveilling party may exert pressure on certain members of the target organization to act as [[informants]] (i.e., to disclose the information they hold on the organization and its members).<ref name="senate-hearing-informants">{{cite web|url= http://www.icdc.com/~paulwolf/cointelpro/churchfinalreportIIId.htm|title=The Use of Informants in FBI Domestic Intelligence Investigations |work=Final Report: Book III, Supplementary Detailed Staff Reports on Intelligence Activities and the Rights of Americans |pages= 225–270 |date= April 23, 1976 |publisher= U.S. Senate Select Committee to Study Governmental Operations with Respect to Intelligence Activities |access-date=March 13, 2009}}</ref><ref>{{Cite web | url= https://www.prisonlegalnews.org/news/2010/jun/15/secret-justice-criminal-informants-and-americas-underground-legal-system/ | title= Secret Justice: Criminal Informants and America's Underground Legal System {{!}} Prison Legal News |website= www.prisonlegalnews.org |access-date= 2016-10-05}}</ref>

Fielding operatives is very expensive, and governments with wide-reaching electronic [[surveillance tools]] at their disposal, rather than gathering the sort of information which operatives can provide, may use less problematic forms of surveillance—such as those mentioned above. Nevertheless, the use of human infiltrators remains common. For instance, in 2007 documents surfaced showing that the [[FBI]] planned to field a total of 15,000 undercover agents and informants in response to an anti-terrorism directive (issued by President [[George W. Bush]] in 2004) that ordered intelligence and law-enforcement agencies to increase their [[HUMINT]] capabilities.<ref name="fbi-informant-network">{{cite web|url= http://blogs.abcnews.com/theblotter/2007/07/fbi-proposes-bu.html|title=FBI Proposes Building Network of U.S. Informants|last= Ross|first= Brian|date= July 25, 2007|work= Blotter|publisher= ABC News|access-date= March 13, 2009
}}</ref>

In some [[home invasion]] cases, thieves may use "[[wiktionary: case the joint|casing surveillance]]” to determine if a victim's property such as a collection of [[firearm]]s are worth stealing.<ref> https://www.cbsnews.com/philadelphia/news/pennsylvania-wrong-house-home-invasion-third-arrest/</ref>