Pathogens are organisms, frequently microorganisms, or components of these organisms, that cause disease. Microbial pathogens include various species of bacteria, viruses, and protozoa.

Patriot Act Terrorist Exclusion List

As mandated by the Patriot Act of 2001 (officially the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act), the United States Department of State Office of the Coordinator for Counterterrorism, in conjunction with the Attorney General, compiles a Terrorist Exclusion List (TEL) of groups and individuals excluded entry into the United States because of terrorist related activities. Individuals and organizations who commit, incite, or aid in the commission of a terrorist act with the intention to cause death or bodily injury may be placed on the TEL.

Patriot Act, United States

The Patriot Act, or Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act, was signed into law on October 26, 2001, in the wake of terrorist attacks on the World Trade Center and Pentagon. The legislation grants law enforcement and intelligence agencies more power to detain and question suspects for longer periods of time, and increases their ability to conduct surveillance operations.

Patriot Missile System

Among the world's most advanced ground-based air defense systems, the Patriot Air and Missile Defense System is in service to the United States and other nations. The missile system, produced jointly by Raytheon and Lockheed Martin Missiles and Fire Control, was a notable feature in the Persian Gulf War of 1991 and Operation Iraqi Freedom in 2003.

Pearl Harbor, Japanese Attack on

On December 7, 1941, Japanese military forces attacked the United States naval fleet anchored at Pearl Harbor on the Hawaiian island of Oahu. The surprise attack nearly devastated the American Pacific fleet.

People Against Gangsterism and Drugs (PAGAD)

People Against Gangsterism and Drugs (PAGAD) was formed in 1996 as a community anti-crime group fighting drugs and violence in the Cape Flats section of Cape Town, South Africa, but by early 1998 it had also become anti-government and anti-Western. PAGAD and its Islamic ally Qibla view the South African Government as a threat to Islamic values and consequently, promote a greater political voice for South African Muslims.

Persian Gulf War

The Persian Gulf War, in which a coalition led by the United States drove Iraqi forces out of Kuwait in early 1991, was one of the most successful campaigns in history. At a cost of less than 300 Allied lives, coalition troops, whose military actions were largely funded by Saudi Arabia, drove out Saddam Hussein's forces.

Peru, Intelligence and Security

Peru is the seat of the ancient Incan Empire, one of the most advanced indigenous civilizations in the Americas. Spanish conquistadors captured the empire in 1533.

Petroleum Reserves, Determination

Petroleum reserves are the recoverable portion of hydrocarbon accumulations that exist below Earth's surface in traps or reservoirs. The quantification of these reserves is essential to the world's effort to utilize hydrocarbons as a major energy source.

PFIAB (President's Foreign Intelligence Advisory Board)

The President's Foreign Intelligence Advisory Board (PFIAB) provides unbiased monitoring of the overall intelligence effort of the United States by continually reviewing the activities of agencies and departments engaged in intelligence work. Through briefings and visits to intelligence installations, the sixteen board members seek to identify deficiencies in the collection, analysis, and reporting of intelligence while eliminating duplication.

Phoenix Program

In an attempt to cripple or eliminate South Vietnamese communist guerilla resistance (the Vietcong) to both United States forces and the U.S.-backed government of South Vietnam, the Phoenix program was allegedly designed to conduct arrest and assassination operations against suspected Vietcong and Vietcong sympathizers. The Phoenix program was developed and operated by the United States Central Intelligence Agency (CIA), the United States Army, and components of several South Vietnamese intelligence and law enforcement agencies.

Photo Alteration

The camera was invented in 1839, and by the next decade, photographers had already begun to manipulate photographic images. Initially, the manipulation was part of the exploration of the artistic potential of the new medium.

Photographic Interpretation Center (NPIC), United States National

The Central Intelligence Agency (CIA) established the National Photographic Interpretation Center (NPIC) in the 1950s to provide skilled interpretation of photographic images obtained by low- and high-flying aircraft, and later by satellites. Originally a unit of the CIA Directorate of Intelligence, NPIC in 1973 transferred to the Directorate of Science and Technology (DS&T).

Photographic Resolution

The term resolution, in the context of photography, refers to the degree to which adjacent objects can be distinguished from one another in a photographic image. Obviously, the higher the degree of resolution—which is a function of the acuity of the photographic equipment used, as well as the abilities of the operator—the better the quality of the photograph.

Photography, High-Altitude

The United States conducts, and has conducted, operations in high-altitude photography for a number of purposes. In addition to intelligence-gathering operations such as that of the CORONA program in the 1960s, civilian undertakings such as those of the U.S.

Playfair Cipher

The Playfair cipher is a method of cryptography invented in 1854 by English physicist Sir Charles Wheatstone (1802–1875). The encryption method was named for Wheatstone's friend, Lyon Playfair, who helped popularize the cipher by successfully lobbying for its official adoption by the British government.

Plum Island Animal Disease Center

The Plum Island Animal Disease Center (PIADC), located on a 180-acre site off the northeastern tip of Long Island, New York, is part of the Department of Homeland Security's efforts to protect the United States food supply. PIADC works to protect U.S.

Poland, Intelligence and Security

Germany's invasion of Poland was the catalyst for World War II. During the Nazi occupation, Polish citizens were subject to interrogation and torture at the hands of officers of the Gestapo, the Nazi secret police.

Politics: the Briefings of United States Presidential Candidates

In accordance with a practice established by President Harry S. Truman, presidential nominees of both major political parties receive intelligence briefings at some point between the summer political conventions and the presidential elections every four years.

Pollard Espionage Case

Jonathan Jay Pollard, a veteran of U.S. Navy intelligence forces, sold secrets to the Israeli government during the 1980s.


A polygraph test is administered to determine whether or not statements made by the subject taking the test are deceptive. During the test, the subject is monitored by a polygraph machine and interrogated by an administrator trained in forensic psychophysiology.

Polymerase Chain Reaction (PCR)

The Polymerase Chain Reaction, or PCR, refers to a widely used technique in molecular biology that has become quintessential in many aspects of DNA analysis with broad-based applications in medicine and forensic investigations. PCR is the amplification of specific sequences of genomic DNA, the genetic material found in virtually all living cells.

Popular Front for the Liberation of Palestine (PFLP)

At one time affiliated with the PLO, the Popular Front for the Liberation of Palestine (PFLP) is a Marxist-Leninist group founded in 1967 by George Habash. The PFLP joined the Alliance of Palestinian Forces (APF) to oppose the Declaration of Principles signed in 1993 and suspended participation in the PLO.

Popular Front for the Liberation of Palestine-General Command (PFLP-GC)

The Popular Front for the Liberation of Palestine-General Command (PFLP-GC) split from the Popular Front for the Liberation of Palestine (PFLP) in 1968, claiming it wanted to focus more on fighting and less on politics. Opposed to Arafat's Palestine Liberation Army (PLO), the PFLP-GC is led by Ahmad Jabril, a former captain in the Syrian Army.

Port Security

Security of national ports has always been a concern for any great power, but between the War of 1812 and the terrorist attacks of September 11, 2001, Americans tended to take such security for granted. Other than a thwarted German attempt to form an alliance with Mexico against the United States—an effort that brought America into World War I—and limited Axis attempts to infiltrate both coasts in World War II, no foreign power launched a successful attack on the contiguous United States prior to the al Qaeda bombings.

PORTPASS (Port Passenger Accelerated Service System)

PORTPASS (Port Passenger Accelerated Service System) is a generic term for programs developed to expedite passage through U.S. national entry systems.

Portugal, Intelligence and Security

Portugal's tumultuous twentieth-century political history affected public perception of the nation's government and intelligence officials. In the 1940s, António de Oliveira Salazar's dictatorship created a secret police force, the International Police for the Defense of the State (PIDE).

Postal Security

Postal security refers to the safeguarding of United States Postal Service (USPS) employees and customers from hazardous materials that may be contained in the mail.

Postal Service (USPS), United States

The United States Postal Service (USPS) is an independent government agency that collects and disseminates the mail to millions of homes and businesses across the country.

Potassium Iodide

Potassium iodide (chemical formula KI) is a salt that is similar in structure and physical character to common table salt (sodium chloride; NaCl). Indeed, potassium iodide is a common commercial additive to table salt, to produce "iodized" salt.