The contemporary term false flag describes covert operations that are designed to deceive in such a way that activities appear as though they are being carried out by individual entities, groups, or nations other than those who actually planned and executed them.
Lance deHaven-Smith states that "The term “false flag” originally referred to pirate ships that flew flags of the home countries of the ships they were approaching to attack and board. The pirates used the false flag as a disguise to prevent their victims from fleeing or preparing for battle. The term today extends beyond naval encounters to include countries that organize attacks on themselves and make the attacks appear to be by enemy nations or terrorists, thus giving the nation that was supposedly attacked a pretext for domestic repression and foreign military aggression."
Operations carried out during peace-time by civilian organizations, as well as covert government agencies , can (by extension) also be called false flag operations if they seek to hide the real organization behind an operation.
Use in warfare
In land warfare such operations are generally deemed acceptable under certain circumstances, such as to deceive enemies providing that the deception is not perfidious and all such deceptions are discarded before opening fire upon the enemy. Similarly, in naval warfare such a deception is considered permissible provided the false flag is lowered and the true flag raised before engaging in battle: auxiliary cruisers operated in such a fashion in both World Wars, as did Q-ships , while merchant vessels were encouraged to use false flags for protection.
Such masquerades promoted confusion not just of the enemy but of historical accounts: in 1914 the Battle of Trindade was fought between the British auxiliary cruiser RMS Carmania and the German auxiliary cruiser SMS Cap Trafalgar which had been altered to look like Carmania. (Contrary to some possibly mendacious accounts, the RMS Carmania had not been altered to resemble the Cap Trafalgar .)
Another notable example was the World War II German commerce raider Kormoran which surprised and sank the Australian light cruiser HMAS Sydney in 1941 while disguised as a Dutch merchant ship, causing the greatest recorded loss of life on an Australian warship. While Kormoran was fatally damaged in the engagement and its crew captured the outcome represented a considerable psychological victory for the Germans. 
Other examples from WWII included a Kriegsmarine ensign in the St Nazaire Raid and captured a German code book: the old destroyer Campbeltown , which the British planned to sacrifice in the operation, was provided with cosmetic modifications that involved cutting the ship's funnels and chamfering the edges to resemble a German Type 23 torpedo boat .
By this ruse the British were able to get within two miles (3 km) of the harbour before the defences responded, where the explosive-rigged Campbeltown and commandos successfully disabled or destroyed the key dock structures of the port.
- Art. 3. A military aircraft must carry an exterior mark indicating its nationality and its military character.
- Art. 19. The use of false exterior marks is forbidden.
This draft was never adopted as a legally binding treaty, but the ICRC states in its introduction on the draft that 'To a great extent, [the draft rules] correspond to the customary rules and general principles underlying treaties on the law of war on land and at sea',  and as such these two non–controversial articles were already part of customary law. 
In land warfare, the use of a false flag is similar to that of naval warfare: the trial of Otto Skorzeny , who planned and commanded Operation Greif , by a U.S. military tribunal at the Dachau Trials included a finding that Skorzeny was not guilty of a crime by ordering his men into action in American uniforms. He had relayed to his men the warning of German legal experts: that if they fought in American uniforms, they would be breaking the laws of war ; however, they probably were not doing so simply by wearing the American uniforms. During the trial, a number of arguments were advanced to substantiate this position and the German and U.S. military seem to have been in agreement.
In the transcript of the trial,  it is mentioned that Paragraph 43 of the Field Manual published by the War Department , United States Army , on 1 October 1940, under the entry Rules of Land Warfare states "National flags, insignias and uniforms as a ruse – in practice it has been authorized to make use of these as a ruse. The foregoing rule (Article 23 of the Annex of the IVth Hague Convention ), does not prohibit such use, but does prohibit their improper use. It is certainly forbidden to make use of them during a combat. Before opening fire upon the enemy, they must be discarded'."
The American Soldiers' Handbook was also quoted by Defense Counsel: "The use of the enemy flag, insignia, and uniform is permitted under some circumstances. They are not to be used during actual fighting, and if used in order to approach the enemy without drawing fire, should be thrown away or removed as soon as fighting begins." Subsequently, the outcome of the trial has been codified in the 1977 Protocol Additional to the Geneva Conventions of 12 August 1949 ( Protocol I ):
Article 37. – Prohibition of perfidy
- 1. It is prohibited to kill, injure, or capture an adversary by resort to perfidy. Acts inviting the confidence of an adversary to lead him to believe that he is entitled to, or is obliged to accord, protection under the rules of international law applicable in armed conflict, with intent to betray that confidence, shall constitute perfidy. The following acts are examples of perfidy:
- (a) The feigning of an intent to negotiate under a flag of truce or of a surrender;
- (b) The feigning of an incapacitation by wounds or sickness;
- (c) The feigning of civilian, non-combatant status; and
- (d) The feigning of protected status by the use of signs, emblems or uniforms of the United Nations or of neutral or other States not Parties to the conflict.
- 2. Ruses of war are not prohibited. Such ruses are acts which are intended to mislead an adversary or to induce him to act recklessly but which infringe no rule of international law applicable in armed conflict and which are not perfidious because they do not invite the confidence of an adversary with respect to protection under that law. The following are examples of such ruses: the use of camouflage, decoys, mock operations and disinformation.
Article 38. – Recognized emblems
- 1. It is prohibited to make improper use of the distinctive emblem of the Red Cross, Red Crescent or Red Lion and Sun or of other emblems , signs or signals provided for by the Conventions or by this Protocol. It is also prohibited to misuse deliberately in an armed conflict other internationally recognized protective emblems, signs or signals, including the flag of truce, and the protective emblem of cultural property.
- 2. It is prohibited to make use of the distinctive emblem of the United Nations , except as authorized by that Organization.
Article 39. – Emblems of nationality
- 1. It is prohibited to make use in an armed conflict of the flags or military emblems, insignia or uniforms of neutral or other States not Parties to the conflict.
- 2. It is prohibited to make use of the flags or military emblems, insignia or uniforms of adverse Parties while engaging in attacks or in order to shield, favour, protect or impede military operations.
- 3. Nothing in this Article or in Article 37, paragraph 1 ( d ), shall affect the existing generally recognized rules of international law applicable to espionage or to the use of flags in the conduct of armed conflict at sea.
A false flag in the cyber domain is slightly different and easier to perpetrate than in other physical theaters of war. Cyber false flags refer to tactics used in covert cyber attacks by a perpetrator to deceive or misguide attribution attempts including the attacker's origin, identity, movement, and/or code/exploitation. It is typically very hard to conclusively attribute cyberattacks to their perpetrators and misdirection tactic can cause misattribution (permitting response and/or counterattack as a condicio sine qua non under international law) or misperception which can lead to retaliation against the wrong adversary.
Cyber false flags can exist in the cyber domain when:
- Weaponized cyber exploits use recycled code/variants from previous attacks;
- Exploits are developed to mimic the scope and complexity of other malware ;
- Exploits are procured rather than developed;
- Exploits are executed from new/unknown operator command servers;
- Malware calls out to or connects to known operator command servers;
- The action or attack is outsourced (e.g. to criminals );
- The compromise is socially engineered to misguide investigations towards other operators;
- The audit trail or lack thereof conceals actual intent or actions with other exploits designed to mislead investigators.
As pretexts for war
In 1788, the head tailor at the Royal Swedish Opera received an order to sew a number of Russian military uniforms. These were then used by the Swedes to stage an attack on Puumala , a Swedish outpost on the Russo-Swedish border, on 27 June 1788. This caused an outrage in Stockholm and impressed the Riksdag of the Estates , the Swedish national assembly, who until then had refused to agree to an offensive war against Russia. The Puumala incident allowed King Gustav III of Sweden, who lacked the constitutional authority to initiate unprovoked hostilities without the Estates' consent, to launch the Russo-Swedish War (1788–1790) .
Second Sino-Japanese War
In September 1931, Japanese officers fabricated a pretext for invading Manchuria by blowing up a section of railway. Though the explosion was too weak to disrupt operations on the rail line, the Japanese nevertheless used this Mukden incident to seize Manchuria and create a puppet government for what they termed the "independent" state of Manchukuo .
World War II
The Gleiwitz incident in 1939 involved Reinhard Heydrich fabricating evidence of a Polish attack against Germany to mobilize German public opinion for war and to justify the war with Poland . Alfred Naujocks was a key organiser of the operation under orders from Heydrich. It led to the deaths of Nazi concentration camp victims who were dressed as German soldiers and then shot by the Gestapo to make it seem that they had been shot by Polish soldiers. This, along with other false flag operations in Operation Himmler , would be used to mobilize support from the German population for the start of World War II in Europe .
The operation failed to convince international public opinion of the German claims, and both Britain and France—Poland's allies—declared war two days after Germany invaded Poland. 
On November 26, 1939, the Soviet army shelled Mainila , a Russian village near the Finnish border. Soviet authorities blamed Finland for the attack and used the incident as a pretext to invade Finland, starting the Winter War , four days later.
The proposed, but never executed, 1962 Operation Northwoods plot by the U.S. Department of Defense for a war with Cuba involved scenarios such as fabricating the hijacking or shooting down of passenger and military planes, sinking a U.S. ship in the vicinity of Cuba, burning crops, sinking a boat filled with Cuban refugees, attacks by alleged Cuban infiltrators inside the United States, and harassment of U.S. aircraft and shipping and the destruction of aerial drones by aircraft disguised as Cuban MiGs.  These actions would be blamed on Cuba, and would be a pretext for an invasion of Cuba and the overthrow of Fidel Castro 's communist government. It was authored by the Joint Chiefs of Staff , but then rejected by President John F. Kennedy . The surprise discovery of the documents relating to Operation Northwoods was a result of the comprehensive search for records related to the assassination of President John F. Kennedy by the Assassination Records Review Board in the mid-1990s. Information about Operation Northwoods was later publicized by James Bamford .
As a tactic to undermine political opponents
The Reichstag fire was an arson attack on the Reichstag building in Berlin on 27 February 1933. The fire started in the Session Chamber, and, by the time the police and firemen arrived, the main Chamber of Deputies was engulfed in flames. Police searched the building and found Marinus van der Lubbe , a young Dutch council communist and unemployed bricklayer, who had recently arrived in Germany to carry out political activities.
The fire was used as evidence by the Nazis that the Communists were beginning a plot against the German government. Van der Lubbe and four Communist leaders were subsequently arrested. Adolf Hitler , who was sworn in as Chancellor of Germany four weeks before, on 30 January, urged President Paul von Hindenburg to pass an emergency decree to counter the "ruthless confrontation of the Communist Party of Germany ".  With civil liberties suspended, the government instituted mass arrests of Communists, including all of the Communist parliamentary delegates. With their bitter rival Communists gone and their seats empty, the National Socialist German Workers Party went from being a plurality party to the majority ; subsequent elections confirmed this position and thus allowed Hitler to consolidate his power.
Historians disagree as to whether Van der Lubbe acted alone, as he said, to protest the condition of the German working class, or whether the arson was planned and ordered by the Nazis, then dominant in the government themselves, as a false flag operation.  
On 4 April 1953, the CIA was ordered to undermine the government of Iran over a four-month period, as a precursor to overthrowing Prime Minister Mohammad Mosaddegh .  One tactic used to undermine Mosaddegh was to carry out false flag attacks "on mosques and key public figures", to be blamed on Iranian communists loyal to the government. 
The CIA project was code-named TP-Ajax , and the tactic of a "directed campaign of bombings by Iranians posing as members of the Communist party", involved the bombing of "at least one" well known Muslim's house by CIA agents posing as Communists. The CIA determined that the tactic of false flag attacks added to the "positive outcome" of Project TPAJAX . 
However, as "the C.I.A. burned nearly all of its files on its role in the 1953 coup in Iran", the true extent of the tactic has been difficult for historians to discern.
Pseudo-operations are those in which forces of one power disguise themselves as enemy forces. For example, a state power may disguise teams of operatives as insurgents and, with the aid of defectors, infiltrate insurgent areas.  The aim of such pseudo-operations may be to gather short or long-term intelligence or to engage in active operations, in particular assassinations of important enemies. However, they usually involve both, as the risks of exposure rapidly increase with time and intelligence gathering eventually leads to violent confrontation. Pseudo-operations may be directed by military or police forces, or both. Police forces are usually best suited to intelligence tasks; however, military provide the structure needed to back up such pseudo-ops with military response forces. According to US military expert Lawrence Cline (2005), "the teams typically have been controlled by police services, but this largely was due to the weaknesses in the respective military intelligence systems."
The State Political Directorate (OGPU) of the Soviet Union set up such an operation from 1921 to 1926. During Operation Trust , they used loose networks of White Army supporters and extended them, creating the pseudo-"Monarchist Union of Central Russia" (MUCR) in order to help the OGPU identify real monarchists and anti-Bolsheviks.
An example of a successful assassination was United States Marine Sergeant Herman H. Hanneken leading a patrol of his Haitian Gendarmerie disguised as enemy guerrillas in 1919. The Patrol successfully passed several enemy checkpoints in order to assassinate the guerilla leader Charlemagne Péralte near Grande-Rivière-du-Nord . Hanneken was awarded the Medal of Honor  and was commissioned a Second Lieutenant for his deed.
During the Mau Mau uprising in the 1950s, captured Mau Mau members who switched sides and specially trained British troops initiated the pseudo-gang concept to successfully counter Mau Mau. In 1960 Frank Kitson , (who was later involved in the Northern Irish conflict and is now a retired British General), published Gangs and Counter-gangs , an account of his experiences with the technique in Kenya ; information included how to counter gangs and measures of deception, including the use of defectors, which brought the issue a wider audience.
Another example of combined police and military oversight of pseudo-operations include the Selous Scouts in the former country Rhodesia (now Zimbabwe ), governed by white minority rule until 1980. The Selous Scouts were formed at the beginning of Operation Hurricane , in November 1973, by Major (later Lieutenant Colonel) Ronald Reid-Daly . As with all Special Forces in Rhodesia, by 1977 they were controlled by COMOPS (Commander, Combined Operations) Commander Lieutenant General Peter Walls . The Selous Scouts were originally composed of 120 members, with all officers being white and the highest rank initially available for black soldiers being colour sergeant . They succeeded in turning approximately 800 insurgents who were then paid by Special Branch, ultimately reaching the number of 1,500 members. Engaging mainly in long-range reconnaissance and surveillance missions, they increasingly turned to offensive actions, including the attempted assassination of Zimbabwe People's Revolutionary Army leader Joshua Nkomo in Zambia . This mission was finally aborted by the Selous Scouts, and attempted again, unsuccessfully, by the Rhodesian Special Air Service .
Some offensive operations attracted international condemnation, in particular the Selous Scouts' raid on a Zimbabwe African National Liberation Army (ZANLA) camp at Nyadzonya Pungwe, Mozambique in August 1976. ZANLA was then led by Josiah Tongogara . Using Rhodesian trucks and armored cars disguised as Mozambique military vehicles, 84 scouts killed 1,284 people in the camp-the camp was registered as a refugee camp by the United Nations (UN). Even according to Reid-Daly, most of those killed were unarmed guerrillas standing in formation for a parade. The camp hospital was also set ablaze by the rounds fired by the Scouts, killing all patients.  According to David Martin and Phyllis Johnson, who visited the camp shortly before the raid, it was only a refugee camp that did not host any guerrillas. It was staged for UN approval. 
According to a 1978 study by the Directorate of Military Intelligence, 68% of all insurgent deaths inside Rhodesia could be attributed to the Selous Scouts, who were disbanded in 1980. 
If the action is a police action, then these tactics would fall within the laws of the state initiating the pseudo, but if such actions are taken in a civil war or during a belligerent military occupation then those who participate in such actions would not be privileged belligerents . The principle of plausible deniability is usually applied for pseudo-teams. (See the above section ). Some false flag operations have been described by Lawrence E. Cline, a retired US Army intelligence officer, as pseudo-operations, or "the use of organized teams which are disguised as guerrilla groups for long- or short-term penetration of insurgent -controlled areas."
Pseudo Operations should be distinguished, notes Cline, from the more common police or intelligence infiltration of guerrilla or criminal organizations. In the latter case, infiltration is normally done by individuals. Pseudo teams, on the other hand, are formed as needed from organized units, usually military or paramilitary . The use of pseudo teams has been a hallmark of a number of foreign counterinsurgency campaigns." 
Similar false flag tactics were also employed during the Algerian civil war , starting in the middle of 1994. Death squads composed of Département du Renseignement et de la Sécurité (DRS) security forces disguised themselves as Islamist terrorists and committed false flag terror attacks. Such groups included the Organisation of Young Free Algerians (OJAL) or the Secret Organisation for the Safeguard of the Algerian Republic (OSSRA)  According to Roger Faligot and Pascal Kropp (1999), the OJAL was reminiscent of "the Organization of the French Algerian Resistance (ORAF), a group of counter-terrorists created in December 1956 by the Direction de la surveillance du territoire (Territorial Surveillance Directorate, or DST) whose mission was to carry out terrorist attacks with the aim of quashing any hopes of political compromise". 
In espionage the term "false flag" describes the recruiting of agents by operatives posing as representatives of a cause the prospective agents are sympathetic to, or even the agents' own government. For example, during the Cold War , several female West German civil servants were tricked into stealing classified documents by agents of the East German Stasi intelligence service, pretending to be members of West German peace advocacy groups (the Stasi agents were also described as " Romeos ," indicating that they also used their sex appeal to manipulate their targets, making this operation a combination of the false flag and " honey trap " techniques). 
The technique can also be used to expose enemy agents in one's own service, by having someone approach the suspect and pose as an agent of the enemy. Earl Edwin Pitts , a 13-year veteran of the U.S. Federal Bureau of Investigation and an attorney, was caught when he was approached by FBI agents posing as Russian agents.
British intelligence officials in World War II allowed double agents to fire-bomb a power station and a food dump in the UK to protect their cover, according to declassified documents . The documents stated the agents took precautions to ensure they did not cause serious damage. One of the documents released also stated: "It should be recognised that friends as well as enemies must be completely deceived." 
While false flag operations originate in warfare and government, they also can occur in civilian settings among certain factions, such as businesses, special interest groups, religions, political ideologies and campaigns for office.
Political campaigning has a long history of this tactic in various forms, including in person, print media and electronically in recent years. This can involve when supporters of one candidate pose as supporters of another, or act as “ straw men ” for their preferred candidate to debate against. This can happen with or without the candidate's knowledge. The Canuck letter is an example of one candidate creating a false document and attributing it as coming from another candidate in order to discredit that candidate.
In 2006, individuals practicing false flag behavior were discovered and "outed" in New Hampshire   and New Jersey  after blog comments claiming to be from supporters of a political candidate were traced to the IP address of paid staffers for that candidate's opponent.
On 19 February 2011, Indiana Deputy Prosecutor Carlos Lam sent a private email to Wisconsin Governor Scott Walker suggesting that he run a "'false flag' operation" to counter the protests against Walker's proposed restrictions on public employees' collective bargaining rights:
If you could employ an associate who pretends to be sympathetic to the unions' cause to physically attack you (or even use a firearm against you), you could discredit the unions ... Employing a false flag operation would assist in undercutting any support that the media may be creating in favor of the unions.  
The press had acquired a court order to access all of Walker's emails and Lam's email was exposed. At first, Lam vehemently denied it, but eventually admitted it and resigned. 
Proponents of political or religious ideologies will sometimes use false flag tactics. This can be done to discredit or implicate rival groups, create the appearance of enemies when none exist, or create the illusion of organized and directed persecution. This can be used to gain attention and sympathy from outsiders, in particular the media, or to convince others within the group that their beliefs are under attack and in need of protection.
In retaliation for writing The Scandal of Scientology , some members of the Church of Scientology stole stationery from author Paulette Cooper 's home and then used that stationery to forge bomb threats and have them mailed to a Scientology office. The Guardian's Office also had a plan for further operations to discredit Cooper known as Operation Freakout , but several Scientology operatives were arrested in a separate investigation and the plan was exposed.
- Agent provocateur
- Black propaganda
- Casus belli
- Covert operation
- Denial and deception
- Front organization
- Joe job , a similar online concept
- State terrorism
- Celle Hole
- CIA Operation Ajax ( United States overthrowing of Mohammed Mossadeq, Prime Minister of Iran, in 1953)
- Gleiwitz incident aka Operation Himmler
- Knights of the Red Branch Inc
- Lavon Affair Israeli attempt to plant bombs in Western targets in Egypt, in blaming Arab elements
- Marxist-Leninist Party of the Netherlands (fake party set up by the Dutch security service)
- Masada Action and Defense Movement (French white supremacists, under the guise of a fake extremist Zionist movement, conducted bombings of Arab targets in France in an attempt to start a war between French Arabs and Jews.)
- Operation Greif during Battle of the Bulge
- Operation Northwoods in the wake of the Cuban Revolution