Preliminary information about an attack on the Westminster Bridge and outside of the Palace of Westminster (home to the British Parliament) in London seems to indicate that it was strikingly similar to recent Islamic State attacks that used vehicles to plow into pedestrians.
Last June, the terror group's "Cyber Caliphate" urged ISIS supporters to use trucks as weapons in densely populated areas.
Within a month, six of these "individual wolves" acted on this suggestion--plotting to slam a massive cargo truck into a Bastille Day celebration on the Promenade des Anglais in Nice, France. The strike killed 86 people and injured 434 others, and ISIS almost immediately took credit for it.
The driver of the truck, a Tunisian citizen who had been living in France, is an ISIS supporter who apparently recruited four other Tunisians and an Albanian with ISIS sympathies into his plot.
In November, ISIS' English-language magazine, Rumiyah, issued a call to use trucks to target Thanksgiving celebrations in the United States, specifically the Macy's Thanksgiving Day Parade.
The Macy's Thanksgiving Parade was not attacked, but the Ohio State University campus was four days later. On November 28th, a Somali refugee apparently radicalized by Islamic State propaganda slammed a Honda Civic into students outside of Watts Hall and then hopped out and began stabbing people, ultimately injuring 13 before a responding police officer shot him to death.
Less than a month later, a Tunisian man who had applied for but was denied asylum in Germany crashed a stolen truck into a Christmas market in Berlin, killing 12 people and injuring 56. ISIS once again claimed responsibility for the attack and even released a video of the suspect (who was killed in a shootout with police in Italy four days later) pledging allegiance to Islamic State leader Abu Bakr al-Baghdadi.
Just two weeks after that, on January 8th, an Arab Israeli citizen killed four uniformed Israeli soldiers and injured 15 others in East Jerusalem when he crashed a truck into them as they got off of a bus. Although ISIS did not claim credit for the attack, Israeli Prime Minister Benjamin Netanyahu said the attack bore all of the hallmarks of an Islamic State strike.
In fact, since the rise of the Islamic State in early 2014, there has been a dramatic rise in vehicle ramming attacks in Israel, Europe, and North America. One count puts the number at 13--five in Israel or the West Bank, four in France, and one each in the United States, Canada, Germany, and now in London.
While it is still far too early in the investigation to know anything for certain about the motive behind this most recent attack, it seems to bear all of the hallmarks of an ISIS-sponsored attack or at the very least an ISIS-inspired attack.