The United States CIA is now known to have sponsored several plans to assassinate Fidel Castor of Cuba. The agency would not send in a CIA operator to do the dirty work but would recruit a nefarious criminal probably a member of the Mafia which is also known as the Cosa Nostra. The hired hand would be recruited clandestinely so the CIA would have plausible deniability. The Mafia was angry with Castro for kicking them out of the country and the subsequent loss of their gambling and other rackets empire in Cuba. President John Fitzgerald Kennedy was aware of these attempts. Supposedly Lee Harvey Oswald assassinated President Kennedy for his attempts to take out Castro.
Assassinating the head of state of some other country is very dirty business and will probably cause a retaliatory attempt to kill the sponsor. Before leaving office, President Gerald Rudolf Ford, Jr. recruited George Herbert Walker Bush (Bush 41) and had him confirmed as Director of the CIA. President Ford then ordered DCI Bush to clean up the agency and stop all pending and future assassination plans.
https://en.wikipedia.org/wiki/Executive_Order_11905
A United States spy is a human intelligence (HUMINT) operative of the Directorate of Operations of the CIA now known as the Clandestine Service. A spy must maintain a low profile and is an individual who uses her/his training and wits instead of a lot of sophisticated equipment. The spy probably does not carry weapons nor use her/his cellphone as a primary means of communication with her/his handler (usually a station chief). The time-honored way of passing messages is the dead drop. The spy goes about her/his business with little or no fanfare.
A United States spy must rely on the CIA to swap a foreign operator for our her/him if he or she has the great misfortune of being arrested as a spy. It is a good tradition to always recover your valuable spy by nearly any means. See the great movie “Bridge of Spies”.