ISIS and al-Qaida have specifically called for the type of attack that just happened in London



It's not clear yet who is responsible for the attack that killed four people in London. But terrorist groups have long been calling for supporters to attack "infidels" with cars.

At least four people were killed in London when lone assailant mowed down dozens of pedestrians on Westminster Bridge in a 4X4 car before killing a police officer with a knife in the grounds of Parliament

London police are treating the incident as a terrorist attack, and an investigation is underway.

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Possible terrorist attack outside UK Parliament in London
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Possible terrorist attack outside UK Parliament in London
LONDON, ENGLAND - MARCH 22: An armed police officer stands guard near Westminster Bridge and the Houses of Parliament on March 22, 2017 in London, England. A police officer has been stabbed near to the British Parliament and the alleged assailant shot by armed police. Scotland Yard report they have been called to an incident on Westminster Bridge where several people have been injured by a car. (Photo by Jack Taylor/Getty Images)
Terror attack outside U.K. Parliament. 2 men down on road. Man with knife/machete got into Parliament and stabbed p… https://t.co/CxeL2zS6uw
Armed police respond outside Parliament during an incident on Westminster Bridge in London, Britain March 22, 2017. REUTERS/Stefan Wermuth
Armed police respond outside Parliament during an incident on Westminster Bridge in London, Britain March 22, 2017. REUTERS/Stefan Wermuth
Armed police have taken the precaution of closing the gates at Buckingham Palace, where the Queen is in residence after today's incident.
LONDON, ENGLAND - MARCH 22: Emergency services vehicles seen on Westminster Bridge on March 22, 2017 in London, England. A police officer was stabbed near to the British Parliament and the alleged assailant shot by armed police. Scotland Yard also reported an incident on Westminster Bridge where one woman has been killed and several people seriously injured by a car. (Photo by Carl Court/Getty Images)
@Reuters photographer at the scene of shootings near House of Parliament in London says at least a dozen injured on Westminster bridge
At least one body seen being covered by a blanket.
People leave after being evacuated from the Houses of Parliament in central London on March 22, 2017 during an emergency incident. Britain's Houses of Parliament were in lockdown on Wednesday after staff said they heard shots fired, triggering a security alert. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
An ambulance is driven through a police cordon outside the Houses of Parliament in central London on March 22, 2017 during an emergency incident. Britain's Houses of Parliament were in lockdown on Wednesday after staff said they heard shots fired, triggering a security alert. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
Police officers surround two individuals on the ground inside the gates of the Houses of Parliament near the entrance, left, in London, U.K. on Wednesday, March 22, 2017. Shots were fired outside Parliament in London, and at least two people are being treated, according to a Bloomberg reporter on the scene. Photographer: Robert Hutton/Bloomberg via Getty Images
Air ambulance just landed at Parliament Square, Westminster, dozens of police cars https://t.co/TZVTO6IzDR
London's air ambulance arrives at the Houses of Parliament in central London on March 22, 2017 during an emergency incident. Britain's Houses of Parliament were in lockdown on Wednesday after staff said they heard shots fired, triggering a security alert. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
A car on Westminster Bridge has just mowed down at least 5 people. https://t.co/tdCR9I0NgJ
We were called at approx 2:40pm to reports of an incident at #Westminster Bridge. Being treated as a firearms incident - police on scene
Incident in #Westminster: We are treating this as a terrorist incident until we know otherwise
Richard tice political campaigner tells me he can see ten bodies on westminster bridge - I can't confirm that from where I am
An armed police officer gestures as he stands guard in Parliament Square, opposite the Houses of Parliament in central London on March 22, 2017 during an emergency incident. British police shot a suspected attacker outside the Houses of Parliament in London on Wednesday after an officer was stabbed in what police said was a 'terrorist' incident. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
People leave after being evacuated from the Houses of Parliament in central London on March 22, 2017 during an emergency incident. Britain's Houses of Parliament were in lockdown on Wednesday after staff said they heard shots fired, triggering a security alert. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
A police officer stops traffic as the Jaguar car of British Prime Minister Theresa May (R) is driven away from the Houses of Parliament in central London on March 22, 2017 during an emergency incident. / AFP PHOTO / Daniel LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
An armed police officer guards inside a police cordon outside the Houses of Parliament in central London on March 22, 2017 during an emergency incident. / AFP PHOTO / Daniel LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
Police officers surround two individuals on the ground inside the gates of the Houses of Parliament near the entrance, left, in London, U.K. on Wednesday, March 22, 2017. Shots were fired outside Parliament in London, and at least two people are being treated, according to a Bloomberg reporter on the scene. Photographer: Robert Hutton/Bloomberg via Getty Images
Police tapes off Parliament Square after reports of loud bangs, in London, Britain, March 22, 2017. REUTERS/Stefan Wermuth
The injured being treated in New Palace Yard at Westminster Palace https://t.co/I7uRyOv2D4
Government source says PM is OK
Police trying to resuscitate one of the Commons attackers. Still seems to be breathing
House of Commons has been suspended following gunshots in Parliament, MPs are leaving the chamber
BREAKING NEWS -- Two people shot outside Houses of Parliament in London
Armed police officers stand guard inside a security cordon, outside of the Houses of Parliament in central London on March 22, 2017 during an emergency incident. Britain's Houses of Parliament were in lockdown on Wednesday after staff said they heard shots fired, triggering a security alert. / AFP PHOTO / DANIEL LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
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The attack mirrors those terrorist groups ISIS and Al Qaeda have publicly called for recently, encouraging supporters to use vehicles as weapons. New York Times terrorism correspondent Rukmini Callimachi noted on Twitter that "stabbing and car-ramming" are "ISIS signatures."

An ISIS video released last year showed a French ISIS member demonstrating how to kill people using knives. The ISIS member also called for attacks in the West.

And in the past year, English-language ISIS propaganda magazines have called for vehicle and knife attacks.

In a recent issue of Rumiyah, a magazine from the terror group aimed at English-language speakers, included an article titled "Just Terror Tactics" that outlined ideal vehicles to use in terror attacks as well as ideal targets.

"Though being an essential part of modern life, very few actually comprehend the deadly and destructive capability of the motor vehicle and its capacity of reaping large numbers of casualties if used in a premeditated manner," the article said.

The article also cited the attack in Nice, France, in July, in which a supposed ISIS supporter killed 86 people by plowing into a crowd with a truck on Bastille Day.

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Vigils around the world for the Nice attack victims
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Vigils around the world for the Nice attack victims
Members of the Australian French community place candles during a vigil in central Sydney, Australia, July 15, 2016 to remember the victims of the Bastille Day truck attack in Nice. REUTERS/David Gray
Members of the Australian French community place candles during a vigil in central Sydney, Australia, July 15, 2016, to remember the victims of the Bastille Day truck attack in Nice. REUTERS/David Gray
Members of the Australian French community place candles during a vigil in central Sydney, Australia, July 15, 2016 to remember the victims of the Bastille Day truck attack in Nice. REUTERS/David Gray
School children offer prayers to pay tribute to the victims of the Bastille Day truck attack in Nice, at a school in Ahmedabad, India, July 15, 2016. REUTERS/Amit Dave
Members of the Australian French community cry as they sing the French national anthem during a vigil in central Sydney, Australia, July 15, 2016 to remember the victims of the Bastille Day truck attack in Nice. REUTERS/David Gray
BANGKOK, THAILAND - JULY 15: French ambassador to Thailand Gilles Garachonk (4th R) joins a vigil to remember the victims of the attack in the French city of Nice at the Alliance Francaise, on July 15, in Bangkok, Thailand. A French-Tunisian attacker killed 84 people as he drove a lorry through crowds, gathered to watch a firework display during Bastille Day celebrations. The attacker then opened fire on people in the crowd before being shot dead by police. (Photo by Dario Pignatelli/Getty Images)
Indian citizens take part in a candle light vigil for the victims of the Mumbai attacks in New Delhi on December 7, 2008.India accuses the banned Islamist movement Laskhar-e-Taiba of training and equipping the 10 militants who stormed India's financial capital by boat to kill 188 people and leaving more than 300 others injured during the 60-hour orgy of violence that saw two luxury hotels and a number of other sites targeted. AFP PHOTO/ Manpreet ROMANA (Photo credit should read MANPREET ROMANA/AFP/Getty Images)
In the courtyard of the apt. building where killer, Maj. Nidal Malik Hasan, lived, (LÂR) Kolleen Alldridge, hugs her son, Gavyn Alldridge, 4, while apartment complex manager, Alice Thompson, huddles close to her friend during a candle light vigil where neighbors are trying to come to terms with the shooting, in Killeen, Texas November 07, 09. THe neighbors all said what a nice person Mr Hasan was. (Photo by Barbara Davidson/Los Angeles Times via Getty Images)
A boy lays a candles to form a heart around a bag reading 'Nice Olympic Swimming' during a candlelight vigil for swimming gold medallist Camille Muffat on March 10, 2015 her hometown, the southeastern French city of Nice, after she died along with nine other people in a helicopter crash in Argentina while filming a reality TV show. France was plunged into mourning on March 10 after three well-known sports stars, including the Olympic champion swimmer and one of the world's best sailors, died when two helicopters filming the survival series 'Dropped' smashed into each other in the rugged mountains of La Rioja province, local officials said. AFP PHOTO / VALERY HACHE (Photo credit should read VALERY HACHE/AFP/Getty Images)
Russian Foreign Minister Sergei Lavrov (L) and US Secretary of State John Kerry lay flowers outside the French Embassy in Moscow on July 15, 2016 in tribute to the victims of the deadly attack in the French Riviera city of Nice. Russian President Vladimir Putin condemned the attack in Nice as an act of 'monstrous evil' in a message to his French counterpart. A gunman smashed a truck into a crowd of revellers celebrating Bastille Day in the French Riviera city of Nice, killing at least 84 people in what President Francois Hollande called a 'terrorist' attack. / AFP / Vasily MAXIMOV (Photo credit should read VASILY MAXIMOV/AFP/Getty Images)
People lay flowers outside the French embassy in Moscow on July 15, 2016 in tribute to the victims of the deadly attack in the French Riviera city of Nice. Russian President Vladimir Putin on July 15 condemned the attack in Nice as an act of 'monstrous evil' in a message to his French counterpart. A gunman smashed a truck into a crowd of revellers celebrating Bastille Day in the French Riviera city of Nice, killing at least 84 people in what President Francois Hollande called a 'terrorist' attack. / AFP / VASILY MAXIMOV (Photo credit should read VASILY MAXIMOV/AFP/Getty Images)
A man lays flowers in front of the French embassy in Kiev French the day after a gunman smashed a truck into a crowd of revellers celebrating Bastille Day, killing at least 84 people on July 15, 2016. A Tunisian-born man zigzagged a truck through a crowd celebrating Bastille Day in the French city of Nice, killing at least 84 and injuring dozens of children in what President Francois Hollande on July 15 called a 'terrorist' attack. / AFP / SERGEI SUPINSKY (Photo credit should read SERGEI SUPINSKY/AFP/Getty Images)
NICE, FRANCE - JULY 15: People visit the scene and lay tributes to the victims of a terror attack on the Promenade des Anglais on July 15, 2016 in Nice, France. A French-Tunisian attacker killed 84 people as he drove a lorry through crowds, gathered to watch a firework display during Bastille Day celebrations. The attacker then opened fire on people in the crowd before being shot dead by police.(Photo by Patrick Aventurier/Getty Images)
NICE, FRANCE - JULY 15: People visit the scene and lay tributes to the victims of a terror attack on the Promenade des Anglais on July 15, 2016 in Nice, France. A French-Tunisian attacker killed 84 people as he drove a lorry through crowds, gathered to watch a firework display during Bastille Day celebrations. The attacker then opened fire on people in the crowd before being shot dead by police.(Photo by Patrick Aventurier/Getty Images)
A sand sculpture about the France truck attack looks at the Bay of Bengal Sea's eastern coast beach at Puri, creating by sand artist Sudarshan Pattnaik to condemn this terror attack near by 65 km away from the eastern Indian city Bhubaneswar, India, on 15 July 2016. (Photo by Biswaranjan Rout/NurPhoto via Getty Images)
A man places flowers in front of the French Embassy in Berlin on July 15, 2016, after the deadly attacks in Nice. A man drove a truck into a crowd watching fireworks in the French Riviera city of Nice, killing at least 84 people. / AFP / John MACDOUGALL (Photo credit should read JOHN MACDOUGALL/AFP/Getty Images)
MOSCOW, RUSSIA - JULY 15, 2016: Flowers outside the French Embassy in Moscow commemorating victims of the 2016 terror attack in the French resort city of Nice. On 14 July 2016, a truck ploughed into a crowd of people celebrating Bastille Day on the Promenade des Anglais. 84 people were killed in the attack. Sergei Savostyanov/TASS (Photo by Sergei Savostyanov\TASS via Getty Images)
A girl holds up a placard during a prayer meet to show solidarity with the victims of the Bastille Day truck attack in Nice, at a school in Ahmedabad, India, July 15, 2016. REUTERS/Amit Dave
A man reacts near bouquets of flowers as people pay tribute near the scene where a truck ran into a crowd at high speed killing scores and injuring more who were celebrating the Bastille Day national holiday, in Nice, France, July 15, 2016. REUTERS/Pascal Rossignol
School children offer prayers to pay tribute to the victims of the Bastille Day truck attack in Nice, at a school in Ahmedabad, India, July 15, 2016. The placard reads, "Tribute to the people killed in the terror attack in France". REUTERS/Amit Dave TPX IMAGES OF THE DAY
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"Vehicles are like knives, as they are extremely easy to acquire," the article said.

The previous issue of Rumiyah included another "Just Terror Tactics" article that provided tips for knife attacks.

Knives "are widely available in every land and thus readily accessible," the article said. "They are extremely easy to conceal and highly lethal, especially in the hands of someone who knows how to use them effectively."

The article also described how to choose a knife and target.

ISIS spokesman Abu Mohammad al-Adnani, now dead, had also called for these attacks. He said in 2014: "If you are not able to find an IED or a bullet, then single out the disbelieving American, Frenchman, or any of their allies. Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him."

Adnani issued a similar directive again in 2015.

Europe in particular has been a focus for ISIS. A 2014 ISIS video encouraged supporters to attack people in France with cars and other easily accessible weapons.

"If you are unable to come to Syria or Iraq, then pledge allegiance in your place — pledge allegiance in France," a French ISIS member says in the video. "Operate within France."

The man then goes on to mention cars specifically: "There are weapons and cars available and targets ready to be hit. ... Kill them and spit in their faces and run over them with your cars."

Al Qaeda has also put out global calls to attack Westerners with cars.

In the second issue of its English-language magazine Inspire, the terrorist group referred to pickup trucks as "the ultimate mowing machine."

"The idea is to use a pickup truck as a mowing machine, not to mow grass but mow down the enemies of Allah," the magazine article states.

Pro-ISIS accounts on the messaging app Telegram, which the terrorist group uses as a platform to disseminate its message, have been celebrating the London attack. But the group has yet to make any claim of responsibility.

ISIS, in particular, has increasingly been relying on external attacks as it has been losing territory in the Middle East, where its self-declared "caliphate" lies.

When the terrorist group first rampaged across Iraq and Syria claiming territory, it encouraged supporters to travel to the Islamic State, but recently ISIS rhetoric has shifted to focus on encouraging people to mount attacks in their home countries.

Sometimes these attacks are directed by ISIS leadership, but sometimes they are carried out by lone actors who don't have any significant contact with ISIS members.

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