Sendero Luminoso (Shining Path, or SL)

Former university professor Abimael Guzman formed Sendero Luminoso (Shining Path, or SL) in the late 1960s, and his teachings created the foundation of SL's militant Maoist doctrine. In the 1980s, SL became one of the most ruthless terrorist groups in the Western Hemisphere; approximately 30,000 persons have died since Shining Path took up arms in 1980.

SENTRI (Secure Electronic Network for Travelers' Rapid Inspection)

The SENTRI (Secure Electronic Network for Travelers' Rapid Inspection) is a component of the Port Passenger Accelerated Service System (PORTPASS) in use at selected border crossings (e.g., crossings at the U.S. and Mexico border in California and Texas) to facilitate quick passage through entry inspection checkpoints.

September 11 Terrorist Attacks on the United States

On September 11, 2001, 19 al-Qaeda-trained terrorists hijacked four U.S. commercial airliners.


Sequencing refers to the techniques used to determine the order of the constituent bases (i.e., adenine, thymine, guanine, and cytosine) of deoxyribonucleic acid (DNA) or protein. Protein sequencing determines the order of the constituent amino acids.

Serbia, Intelligence and Security

Following the dissolution of Yugoslavia in 1989, after the fall of Soviet communism in Eastern Europe, the Balkan region fell into conflict. The former Yugoslav provinces splintered into several independent nations, but Serbia and Montenegro chose to remain a communist dominated state.

Sex-for-Secrets Scandal

On December 14, 1986, a United States Marine who had been serving as an Embassy guard in Moscow and Vienna turned himself in to CIA officials. The Marine, Sergeant Clayton J.

Ships Designed for Intelligence Collection

The concept of using ships as modern intelligence-gathering platforms evolved, along with larger modern ideas of intelligence operations in general, from World War II. The Cold War saw the deployment, on both the Soviet and American sides, of ships tasked with gathering communications and electronic intelligence.

"Shoe Bomber"

On December 22, 2001, al-Qaeda sympathizer Richard Reid attempted the mid-flight destruction of an American Airlines aircraft bound from Paris to Miami flight with 197 people on board. Reid attempted to destroy the flight with plastic explosives concealed in his shoes that were capable of blowing a hole in the plane's pressurized fuselage.

Shoe Transmitter

A popular weekly situation comedy called "Get Smart" ran on the American Broadcasting Corporation television network in the United States for five seasons in the 1960s. In the show—a spoof of spies and espionage organizations—the lead character, Maxwell Smart, often communicated with his colleagues via a "shoe phone." The television series and the espionage equipment were conceived as a nonsensical spoof of the spy movies that were in vogue at that time.

Short-Wave Transmitters

Short-wave radio transmission and reception occurs in the range somewhere between 2 and 30 MHz (megahertz, or million cycles per second). Because these signals are capable of propagating over a greater distance than either AM or FM radio, shortwave is the preferred medium for radio broadcasting to remote locations.

SIGINT (Signals Intelligence)

Signals intelligence, or SIGINT, is one of the four major forms of intelligence, along with human, imagery, and measurement and signatures intelligence (HUMINT, IMINT, and MASINT respectively). As its name suggests, it is intelligence derived from the interception of signals, including communications signals, electronic emissions, and telemetry.


A silencer is an effort to suppress sound by means of an attachment to a firearm. Generally, a six- to twenty-inch steel, titanium, or aluminum alloy barrel addition designed to work with a particular weapon, silencers have also been constructed from other materials such as plastic soft drink bottles.

Skunk Works

"Skunk Works" is the nickname for the headquarters of advanced development programs for Lockheed Martin Aeronautics Company at Palmdale, California, some 80 miles (128 km) north of Los Angeles in the Antelope Valley. Established in 1943 by what was then known as the Lockheed Aircraft Corporation, the Skunk Works has been the birthplace of numerous extraordinary aircraft, including the U-2 and SR-71 reconnaissance planes and the F-117A stealth fighter.

Slovakia, Intelligence and Security

The security and intelligence agencies of Slovakia work in the shadow cast by their communist-era predecessors. In a situation common among many nations of the former Soviet bloc, Western observers have noted a distressing degree of continuity between the old police-state security and intelligence apparatus, and that of the new democratic state.

Slovenia, Intelligence and Security

The principal intelligence agency in Slovenia is the Slovenska Obvesèevalno-Varnostna Agencija (SOVA; Slovenian Intelligence and Security Agency). Domestic security priorities set by the national assembly guide SOVA, which is responsible for collecting information both at home and abroad on groups or individuals who might threaten the state and its constitutional system.


Smallpox is an infection caused by the variola virus, a member of the poxvirus family. The disease is highly infectious.

Smallpox Vaccine

Smallpox, or variola major, is a highly contagious disease that is caused by the variola virus. The name smallpox comes from the Latin word for spotted.

SOE (Special Operations Executive)

A World War II-era British secret service division, the Special Operations Executive (SOE), formed on July 19, 1940, to coordinate subversion and sabotage in enemy-occupied countries. SOE agents distributed propaganda, blew up bridges, directed air strikes, destroyed factories, and taught resistance tactics.

Soldier and Biological Chemical Command (SBCCOM), United States Army

The United States Army Soldier and Biological Chemical Command (SBCCOM) is a support organization focused on the development, response to, and safe handling of chemical weapons. Formed in 1998 from the merger of two earlier groups, SBCCOM is heavily involved in preparedness training for both military and civilians to prevent or, if necessary, respond to terrorist attacks.

Solid-Phase Microextraction Techniques

Solid-phase microextraction (SPME) is a chemical technique designed to detect chemical compounds. In its forensic application, it is used to find chemical warfare agents, high explosives, or illegal drugs.


Soman (or "GD") is a synthetic (human-made) compound that affects the functioning of nerves. As such, Soman is one of a group of chemicals that are known as nerve agents.


SONAR, an acronym for Sound Navigation and Ranging, is a technique based on echolocation used for the detection of objects underwater.

SOSUS (Sound Surveillance System)

Utilizing the unique properties of sound transmission in water, during the 1950s, the United States Navy developed the Sound Surveillance System (SOSUS). Code named "Jezebel" the SOSUS system provided critical monitoring of Soviet submarine and ship movements, especially through the critical ocean gaps between Greenland, Iceland, and the United Kingdom (the GI-UK gap).

South Africa, Intelligence and Security

After decades of segregation under the system of apartheid, South Africa in 1994 became a multiracial democracy. In place of the old regime, which included the dreaded Bureau of State Security—BOSS, a agency portrayed memorably by British author Graham Greene in The Human Factor (1978)—the new South Africa had its own intelligence and security organizations.

South Korea, Intelligence and Security

South Korea, or the Republic of Korea (ROK), has an intelligence and security apparatus that is, in many respects, modeled on that of the United States. The ranking system in the defense forces is similar to that of the U.S.

Soviet Union (USSR), Intelligence and Security

On December 20, 1917, less than two months after the October Social Revolution in Russia, the All-Russian Special Commission for Combating Counter-revolution and Sabotage (VChK) was created in the new Soviet Russia. The agency was created by decree of the Council of the People's Commissar (SNK), the government at that time, "for combating counter-revolution and sabotage." The main aim of the commission was the suppression of any opposition to the new regime in any form, and in this case "suppression" very often meant physical extermination of persons who did not approve the regime.

Space Shuttle

Although NASA is a civilian space agency, the United States military has used the space shuttle fleet to carry classified military payloads into space. The Department of Defense (DoD) had generally received priority in scheduling national security related flights.

Spain, Intelligence and Security

Spain is one of the few Western countries in which a single agency handles both internal and external intelligence. This is CNI, or Centro Nacional de Inteligencia (National Intelligence Center).

Spanish-American War

In the late nineteenth century, the United States grew in industrial and economic strength. By the 1880s, the nation was one of the most robust in the Western Hemisphere, wielding increasing power in the region despite a stated policy of neutrality.

Special Collection Service, United States

The National Security Agency (NSA) has a reputation as the most secretive major component of the United States intelligence community, but it is a veritable open book in comparison to one of its subsidiary organizations, the Special Collection Service (SCS). The latter is known to be engaged in communications intelligence (COMINT), primarily in hostile countries, and its personnel appears to include both NSA and Central Intelligence Agency (CIA) operatives.