I.

Introduction

National Security Agency, United States government agency created in 1952 to conduct worldwide electronic surveillance, break foreign codes and ciphers, and develop encryption systems for the protection of United States government communications. A code or cipher is a system of letters, numbers, or symbols that convert normal language into a secret communication that can be understood only by someone who has the “key” for deciphering the code. Encryption is the process of turning normal language into code. See also Cryptography.

The National Security Agency (NSA) is the largest and most secret U.S. intelligence agency. Located on hundreds of acres of Fort George G. Meade, halfway between Washington, D.C., and Baltimore, Maryland, it produces the vast majority of intelligence reports used by the federal government. Most of those reports are the product of the agency’s worldwide network of ground-, ship-, air-, and space-based eavesdropping systems. Other reports come from the agency’s foreign partners, primarily in the United Kingdom, Canada, Australia, and New Zealand, as well as a number of other friendly countries.

Another area of focus for the agency is foreign noncommunications signals, such as radar and guided missile telemetry. By intercepting and analyzing radar signals, technicians are able to find ways to jam or deceive them. Eavesdropping on telemetry signals from foreign missiles and spacecraft provides the agency with a great deal of intelligence on the capabilities and accuracy of those systems.

II.

Responsibilities

The NSA serves as a collector of intelligence for other federal agencies involved in defense, intelligence, and national security. These other agencies provide the NSA with information about subjects and targets in which they have interest, such as a new Chinese missile system or terrorist suspects in Turkey, for example. The NSA then programs its various eavesdropping systems to scan foreign and international communications to obtain relevant phone calls, e-mails, or other types of messages. Once these are collected, agency analysts review the intercepts and then write reports for the organizations that requested the information, as well as other agencies concerned with similar topics. Copies of the reports are also kept in large NSA computer databases that can be searched months or years in the future.

The NSA’s form of espionage is known as signals intelligence, or “sigint.” Other intelligence agencies specialize in different collection techniques. The Central Intelligence Agency (CIA), for example, concentrates largely on “humint,” human intelligence from spies and agents recruited by CIA officers. Another agency, the National Geospatial-Intelligence Agency, focuses on “geoint,” high-resolution imagery of ground targets captured by imaging satellites, specially rigged aircraft, or drones. And the Defense Intelligence Agency (DIA) is largely responsible for military intelligence and “masint,” measurement and signature intelligence, a specialty that derives intelligence from the capture of such things as radiation and chemical particles.

Within the United States intelligence community, NSA’s signals intelligence has always been considered far more reliable than intelligence collected from human sources, such as foreign defectors and agents-in-place. The human agents, for example, may be passing false information to obtain a visa or money or because they are double agents working for a foreign government. But with intercepted telephone, data, and Internet communications from unsuspecting foreign officials or terrorists, chances that the intelligence is deliberately manipulated are far fewer.

Nevertheless, with the end of the Cold War and the new focus on terrorism, the NSA has had a difficult time adjusting. In the past, the agency could rely on a constant flow of communications, much of it unencrypted, coming from army, navy, and air force units belonging to the Union of Soviet Socialist Republics (USSR), the Cold War foe of the United States that dissolved in 1991. But today, terrorist cells are designed to limit communications to just a few people. And within the group, most of the communication is through face-to-face meetings or, occasionally, through the use of random and anonymous cyber cafes and disposable cellular phones. Overcoming these new challenges is proving difficult for the agency.

III.

Structure

By tradition, the director of the NSA has always been a three-star general or admiral, and the deputy director has always been a career agency employee. The NSA director reports to both the secretary of defense and director of national intelligence. The NSA director is in charge of the tens of thousands of civilians who work mainly at the agency headquarters and a number of field locations in the United States and around the world. The NSA director is also chief of the Central Security Service, the NSA’s own military organization. As chief of the security service, the director is responsible for thousands of Army, Navy, Marine, and Air Force personnel who operate many of the agency’s listening posts around the world.

In 2005 Army Lieutenant General Keith Alexander succeeded Air Force Lieutenant General Michael V. Hayden as NSA director. General Hayden received his fourth star and went on to become the principal deputy director of national intelligence and, in 2006, the director of the Central Intelligence Agency.

Internally, the agency is divided according to function. The largest organization is the Directorate of Sigint Operations, which is responsible for the agency’s worldwide eavesdropping activities. The Information Assurance Directorate, on the other hand, works to ensure that no foreign power has the ability to penetrate official U.S. communications. A third large organization, the Technology and Systems Directorate, specializes in research and development.

IV.

Gathering Intelligence and Reporting Findings

The NSA conducts its signals-intelligence mission from a variety of “platforms.” Platforms are essentially devices that enable the NSA to eavesdrop on communications. Platforms may be located on or below the ocean surface, on land, or in air or space.

A.

Subocean

Today, a large percentage of international telecommunications travels over fiber optic cables that crisscross the world’s oceans and seas. Packed within these undersea cables are thousands of thin glass fibers about the size of a human hair. When electrical signals are converted to light waves, millions of telephone calls and Internet messages can be transmitted over these cables simultaneously. Using specially modified submarines, such as the USS Jimmy Carter, the NSA is able to tap into many of these cables. However, because it is a very complex technological operation, the agency often tries to short-cut the process by reaching secret agreements with companies that own or maintain the cable landing stations where the cables come ashore. Within the United States, this effort has become very controversial and has led to a number of ongoing lawsuits against telecommunications companies, such as AT&T Inc. and Verizon Communications Inc.

B.

Sea

During the 1960s the NSA had a fleet of ships designed specifically for eavesdropping along the coasts of target countries. But after several attacks, including one by Israel against the USS Liberty that resulted in the death of 34 crewmembers and the wounding of nearly 200 others, the NSA gave up its navy. Today, portable equipment, including large self-contained vans, is placed on a wide variety of U.S. Navy ships for short- and long-term missions to sensitive areas.

C.

Land

Most of the NSA’s signals-intelligence activities take place on sprawling land-based listening posts both in the United States and in many foreign nations. They are made up of acres of large radome-covered parabolic dishes, some up to 46 m (150 ft) across, as well as a variety of other types of antennae. For reasons of secrecy and to avoid interference from heavy concentrations of electronic signals, like those found in cities, these stations are normally located in remote areas, such as Sugar Grove in West Virginia, and Menwith Hill in Yorkshire, England. These listening posts, also known as intercept stations, collect a wide variety of communications traffic transmitted to Earth from commercial satellites, such as Intelsat, and government satellites from key target countries, including Russia and China. See also Communications Satellite.

Under a program known as Echelon, the United States, the United Kingdom, Canada, Australia, and occasionally New Zealand, share intelligence from their own regions of the world. The signals intelligence agencies in each country are linked by computer, and member nations can ask other members to focus on targets of interest to them.

D.

Air

For many years, specially rigged reconnaissance aircraft such as the U-2 and TR-1 have been used to collect communications and electronic intelligence during flights over or alongside target countries. Target countries may be allies as well as hostile nations. Increasingly, this mission is being conducted with unmanned aerial vehicles such as the small Predator drone and the large Global Hawk unmanned aircraft. They have been used extensively in the conflicts in Afghanistan and Iraq.

E.

Space

Because of the enormous amounts of communications transmitted within and between countries through the use of satellites, the NSA makes extensive use of its own eavesdropping satellites both in geostationary equatorial orbit (GEO) over the Earth and also in low Earth orbit. GEO satellites orbit Earth around the equator at a very specific altitude that allows them to complete one orbit in the same amount of time that it takes Earth to rotate once. As a result, these satellites stay above one point on Earth’s equator at all times. The altitude of a GEO satellite is about 35,800 km (about 22,200 mi) above Earth’s surface. A satellite in low Earth orbit (LEO) orbits at an altitude of 2,000 km (1,200 mi) or less. As microwave signals, which travel in a straight line, are transmitted from terrestrial relay tower to relay tower they eventually continue on into deep space. Using highly sophisticated geostationary satellites, the NSA is able to target the communications in which it is interested. Once intercepted by the satellite, the signals are then either retransmitted down to an NSA listening post or passed directly to NSA headquarters at Fort Meade through relay satellites. Sigint satellites in LEO orbit are often used to target ships and submarines at sea. (See also Artificial Satellite.)

Eventually, sometimes after some initial filtering, all the communications collected ends up back at NSA headquarters or one of its major processing stations in Georgia, Texas, or Hawaii. There the intercepts are prioritized, translated, analyzed, and turned into highly secret reports that are forwarded to the government officials responsible for dealing with the topics discussed.

V.

History of the National Security Agency

A.

Precursors to the NSA

A.1.

MI-8

On June 29, 1917, a former State Department code clerk, Herbert O. Yardley, took charge of Section Eight of Military Intelligence, responsible for all code and cipher work in the division. It was the birth of MI-8, the earliest ancestor of the present-day National Security Agency. Among the key units established by Yardley was the Code and Cipher Solution Subsection, which eventually deciphered a total of 10,735 messages sent by foreign governments.

With the signing of the armistice that ended World War I on November 11, 1918, Yardley faced an uncertain future. For some time he had been concerned about what lay ahead now that America had entered a time of peace. But following a series of high-level discussions concerning the possibility of retaining a capability to eavesdrop on foreign communications, General Marlborough Churchill, director of military intelligence, recommended to the Army chief of staff that MI-8 'be retained in toto.”

A.2.

The Black Chamber

Yardley then proposed that the new peacetime code-breaking organization be made up of ten civilian code and cipher experts. The total budget was set at $100,000, $40,000 of which was to be paid by the State Department and $60,000 by the War Department. The War Department was to submit its expenditures in a “confidential memorandum” so that the expenditures were not subject to review by the comptroller general and were kept secret, probably the first instance in U.S. history of a secret intelligence budget. On May 20, 1919, America’s Black Chamber—a name taken from the secret mail-opening offices in Britain during the Middle Ages—was born.

For reasons of security, as well as the fact that the State Department’s portion of the budget could not by law be spent within the District of Columbia, Yardley set up shop in New York City. To hide even further the true nature of the work, Yardley formed a commercial code business called Code Compilation Company. If anyone ventured in through the front door, he would find an apparently legitimate company. The firm did produce a commercial code, the Universal Trade Code, which it was able to sell profitably.

Despite his modest facilities and budget, within seven months Yardley was able to solve his primary target, the complex Japanese code system. It was to be by far the most important achievement of the Black Chamber and Yardley’s greatest personal triumph. Throughout the rest of the 1920s the organization successfully solved more than 10,000 messages, most of them diplomatic, from Argentina, Brazil, China, Costa Rica, Cuba, Germany, Japan, Liberia, Mexico, Nicaragua, Panama, Peru, the Soviet Union, El Salvador, Santo Domingo (the Dominican Republic), Spain, France, England, and even the papal codes of the Vatican.

The Black Chamber did not last long, however. The U.S. Secretary of State under President Herbert Hoover, a tradition-minded diplomat named Henry L. Stimson, became outraged upon learning that the Black Chamber was spying on foreign governments. “Gentlemen do not read each other's mail,” he was alleged to have said, and with that he did away with the organization. At midnight on October 31, 1929, the doors to the Black Chamber officially closed.

A.3.

Signal Intelligence Service

The closing of the Black Chamber did not mean that code-breaking ceased. Code-breaking would go on, but now by the Army instead of the State Department. Yardley went on to write an infamous book about his experiences, The American Black Chamber (1931). Meanwhile, William F. Friedman, a one-time geneticist and Army cryptologist, became America’s chief code-breaker as head of the newly formed Signal Intelligence Service (SIS). To fill the six additional slots of his tiny organization, Friedman picked Frank B. Rowlett, a recent science graduate from a small college in southern Virginia; Abraham Sinkov, a short, bespectacled high school teacher from New York; Solomon Kullback, a Brooklynite with a master’s degree from Columbia University; John B. Hurt, an expert in Japanese; and Harry Lawrence Clark as an assistant cryptographic clerk.

From 1930 until 1937 the total annual budget of the SIS never exceeded $17,400. By the time German troops marched into Poland on September 1, 1939, beginning World War II, the SIS had increased its staff only from 7 to 19. During World War II the British were able to focus on deciphering German codes, having obtained an Enigma cipher machine used by the Germans to encrypt their cables. Friedman and his small band of code-breakers concentrated on Japan and its extremely complex new cipher machine that the SIS codenamed Purple. Despite never having even seen what the actual machine looked like, the team managed to put together a spaghetti-like maze of multicolored wire, contacts, and switches and came up with a contraption that, on September 25, 1940, issued its first totally clear, ungarbled text of a Purple message. Friedman’s team had accomplished the near impossible—they had created a perfect clone without ever having seen its twin.

As the Purple intercepts were received, both the SIS and the Navy’s codebreakers often competed to solve them. The Navy team, known by its organizational designation, OP 20 G, was led by Commander Laurance Safford, regarded as the father of naval cryptology. Together, on a daily odd-even basis, they were responsible for deciphering the Purple diplomatic traffic.

A.3.a.

Warning of Pearl Harbor Attack

In the early morning hours of Sunday, December 7, 1941, the Navy’s listening post at Bainbridge Island in Puget Sound, Washington, intercepted several messages transmitted between Tokyo and Washington, D.C., over the commercial circuits of Mackay Radio & Telegraph Company. Bainbridge in turn retransmitted them to OP 20 G in Washington, D.C. Encrypted in Purple, they were the final parts of a long, 14-part message from Japan’s Foreign Office to its Washington, D.C., embassy.

By 9 am in Washington, the messages had been deciphered and their meaning understood: Japan had ordered its ambassador to break off negotiations with the United States at precisely 1 pm. It was the penultimate act before war. Although none of those with knowledge of the message knew precisely where the Japanese would strike, it was clear that a warning must be sent out immediately to American forces in the Pacific. Nine o’clock in the morning in Washington, D.C., was only a few hours after midnight in Hawaii.

But despite having four hours’ advance notice of a likely impending attack, the warning message, sent as a regular commercial telegram, finally reached Honolulu’s RCA telegraph office at 7:33 am. There it was placed unceremoniously in its proper pigeonhole for later delivery. At 7:55 am, the Japanese attack began as the first bomb smashed into a seaplane ramp on Ford Island in Pearl Harbor. Before the last bomb fell two hours later, Americans would give their lives at the rate of almost 30 a minute.

Nearly two hours after that final fatal explosion, a messenger for RCA entered Fort Shafter in Hawaii and handed the envelope containing the warning message to an officer in the Signal Division. At 2:40 pm the officer passed the message to the decoding officer, and 20 minutes later, more than 15 hours after the ominous Purple message was first intercepted, the warning at last reached the general in charge.

B.

Creation of NSA

Determined to prevent another Pearl Harbor-style disaster during the Korean War (1950-1953), U.S. President Harry S. Truman decided to pull together the nation’s divided cryptologic groups into a single, powerful, and highly secret civilian agency. Bypassing Congress, he issued a top secret memorandum in October 1952 creating what is today the largest and most secret intelligence organization in the country, the National Security Agency.

Because it was created by a secret order, the NSA never received an official charter as the CIA did. The CIA was created by an act of Congress in 1947, but for many years few members of Congress even knew the NSA existed. The legislation creating the CIA mandated that the agency could not conduct any operations in the United States. But since the NSA was not created by an act of Congress, no such prohibition explicitly applied to the agency. Perhaps partly as a result, the NSA’s history has been replete with controversy, ranging from its role in the Cold War and the Vietnam War to its more recent electronic surveillance following the September 11, 2001, terrorist attacks in the United States.

C.

Operation Shamrock

When it was first created, the NSA inherited an intelligence-gathering program called Operation Shamrock that had begun in August 1945 under its predecessor, the renamed SIS known as the Signal Security Agency (SSA). The program involved the interception of all cables entering and leaving the United States.

D.

First Defection

The NSA remained so secretive during the first decades of its existence that the announcement in 1960 of two defectors from the agency sent shock waves throughout the government. The defectors showed up at a press conference in Moscow, then the capital of the Union of Soviet Socialist Republics (USSR) and America’s Cold War enemy. The two former NSA cryptanalysts revealed numerous secrets, including the existence of a secret program to collect intelligence about the Soviets’ radar-tracking abilities. The program involved flying U.S. military aircraft into Soviet airspace to test the response of Soviet radar. The secret flights came at a particularly tense time in relations between the two nuclear-armed nations.

The defectors also disclosed that the United States was eavesdropping on allies, such as France, Indonesia, Italy, Turkey, and Uruguay. But perhaps more importantly, the defectors’ press conference gave the world its first look inside the NSA itself. Some high-ranking Defense Department officials regarded the defections as the biggest security breach since the British physicist Klaus Fuchs disclosed details of the Manhattan Project and the atomic bomb to the Soviets in the 1940s.

E.

Cuban Missile Crisis

Not all of the NSA’s operations during the Cold War raised the prospects of armed confrontation with the Soviet Union. During the Cuban Missile Crisis in 1962, NSA intercepts may have saved the two nations from a nuclear war. Those intercepts showed clearly that Soviet ships headed to Cuba with offensive arms were turning around, rather than heading toward a U.S. naval blockade, thus narrowly averting a clash that could have led to disaster.

F.

Vietnam War

The NSA also turned out to be at the heart of a controversy over whether an alleged “attack” in 1964 on a U.S. Navy ship in the Gulf of Tonkin actually occurred. The supposed attack led to full U.S. involvement in the Vietnam War (1957-1975). Although U.S. military advisers had long aided the South Vietnamese Army in Vietnam’s civil war, a full deployment of U.S. military forces in Vietnam only occurred after the U.S. Congress passed the Gulf of Tonkin resolution. That resolution was based on a claim of “unequivocal proof” furnished by the NSA supposedly showing that North Vietnamese gunboats had attacked both the USS Turner Joy and the USS Maddox in international waters in the Gulf of Tonkin on August 4, 1964.

The alleged attack occurred after an earlier incident on August 2 in which North Vietnamese gunboats fired torpedoes at the Maddox, which had crossed into North Vietnam’s declared territorial waters. Later investigations showed that the “unequivocal proof” cited by Secretary of Defense Robert McNamara of an August 4 attack was actually based on NSA intercepts from the August 2 incident. A congressional investigation of the alleged incident later showed that the August 4 attack probably did not occur and that the U.S. Congress had been misled by the administration of President Lyndon Johnson into approving a full-scale military escalation. In 2005 the release of previously classified NSA documents added more support to the finding that there was no August 4 attack in international waters. Among the documents was an account by an NSA historian who concluded that NSA intelligence officers “deliberately skewed” the evidence of an attack and failed to pass on information to superiors showing that no attack occurred on August 4.

G.

Congressional Hearings

Not until 1975 did the United States Congress finally become familiar with some of the previously secret workings of the National Security Agency. That year Congress learned that the NSA had been spying on American citizens. In hearings before a special committee of the House of Representatives in August 1975, chaired by New York Democrat Otis Pike, then CIA director William E. Colby referred publicly for the first time to details of Operation Shamrock. In disclosing that the NSA eavesdropped on international communications, Colby also admitted that it was technically impossible for the agency to separate out communications from U.S. citizens.

In subsequent hearings later that year before the Senate Intelligence Committee, chaired by Democrat Frank Church of Idaho, the NSA director revealed that the agency had eavesdropped on the conversations of Americans who had been “watch-listed” by other U.S. intelligence agencies and the U.S. military. Most of these Americans were involved in the anti-Vietnam War movement, the Black Power movement, and the civil rights movement. Among the prominent Americans watch-listed were civil rights leader Martin Luther King, Jr., antiwar activist and pediatrician Benjamin Spock, actress Jane Fonda, and folksinger Joan Baez. From 1967 to 1973, the NSA director told the Church Committee, the agency had issued reports on 1,680 watch-listed American citizens.

The congressional hearings led to the passage in 1978 of the Foreign Intelligence Surveillance Act (FISA), which for the first time outlined what the NSA was and was not permitted to do. FISA prohibited NSA from the wholesale collection of telegrams and cables, as it had done under Operation Shamrock, and it also outlawed the compilation of watch-lists containing the names of U.S. citizens. In order to eavesdrop on the U.S. end of an international communication involving a U.S. citizen or a permanent alien resident in the United States, FISA required the NSA or any other U.S. intelligence agency to obtain a warrant from a special court known as the Foreign Intelligence Surveillance Court. For a warrant to be approved, the intelligence agency had to show grounds that the person they wished to target was an agent of a foreign power or was involved in terrorism or espionage.

H.

Transitioning to the 21st Century

The legal parameters set by the FISA standards and the ending of the Cold War in 1991 kept the NSA largely out of the headlines through the remainder of the 20th century. But the al-Qaeda-organized terrorist attacks of September 11, as the 21st century began, posed new challenges for the NSA and once again put it in the spotlight.

In the aftermath of the terrorist attacks, the September 11 Commission was created to probe how the airplane hijackers had eluded U.S. intelligence agencies. The commission’s final report focused largely on the failure of the Federal Bureau of Investigation (FBI) and the CIA to share information and work together. For example, the NSA in December 1999 had learned about a man named Khalid by intercepting a telephone call to a suspected al-Qaeda safe house in Yemen. An NSA report notified the CIA about Khalid, who was to become one of the September 11 hijackers. The CIA soon learned his last name, Almihdhar, and that he had a multi-entry visa allowing him to visit the United States. Nevertheless, his name was not submitted to the U.S. State Department’s terrorist watch-list—known as TIPOFF and intended to deny U.S. entry to suspected terrorists—until August 23, 2001. And although the NSA continued to pick up Almihdhar’s phone calls to the safe house in Yemen, the agency never discovered that his calls were coming from within the United States. The FBI claimed that the CIA failed to share the information on Almihdhar. The CIA denied the charge, but congressional investigators backed the FBI claim.

After September 11 it was learned that some of the hijackers had actually lived within sight of NSA headquarters. Perhaps more damaging to its reputation, NSA intercepts of communications from suspected al-Qaeda locations in Afghanistan on September 10, 2001, containing the phrases “the match begins tomorrow” and “tomorrow is zero hour,” were not translated until September 12.

The September 11 attacks and the possibility of more terrorism directed at the United States and U.S. interests pointed to a significant problem for the NSA. Telecommunications companies were now increasingly relying on fiber-optic cables, and terrorists were learning to avoid satellite telephones, relying instead on face-to-face communications, prepaid phone cards, throwaway cell phones, and other methods.

In the final days of Operation Shamrock in the 1970s, the NSA had realized that an increasing amount of international telecommunications was being relayed by satellite. As a result, the agency no longer needed the cooperation that telecommunications companies had given them under Operation Shamrock. Using radome-covered dish antennae and their own satellites, the NSA could intercept satellite communications on their own. But with the growth of fiber-optic cable usage, the NSA reportedly again sought the cooperation of the telecommunications firms.

Following the September 2001 terrorist attacks, the NSA began a controversial program of warrantless domestic eavesdropping. On orders from the administration of President George W. Bush, the agency began an operation called the Terrorist Surveillance Program (TSP). The program targeted the international communications of people suspected of communicating with terrorist organizations, without first obtaining a FISA warrant. The program reportedly included the cooperation of major telecommunications firms, such as AT&T Inc. and Verizon Communications Inc. These firms allegedly allowed the NSA to monitor communications from ground stations in the United States so that the agency did not have to tap into subocean fiber-optic cables.

After the program was disclosed in 2005, however, civil liberties advocates and members of Congress raised questions about its legality. The American Civil Liberties Union (ACLU) and the Electronic Frontier Foundation challenged the program in the courts. In 2006 a U.S. federal district court judge found that the surveillance program not only violated FISA but also the First and Fourth amendments to the U.S. Constitution. In January 2007 the Justice Department announced that it was ending the TSP and again obtaining warrants from the FISA court. Nevertheless, many civil liberties advocates were concerned that the agency was now asking for broad warrants covering tens or hundreds of people, rather than the individual warrants required by FISA. Also, civil libertarians were concerned that the president could at any time simply return to the warrantless procedures.