In the immediate aftermath of what police are describing as a terrorist incident in and around Parliament, at least three facts stand out suggesting that the attacks are similar to those carried out over the last two years by Isis supporters in Paris, Nice, Brussels and Berlin. .

The similarities with the events today are in the targets of the attacks which in all cases were ordinary civilians, but the means of trying to cause mass casualties differs. In Nice, Berlin and London no fire arms were used by the attackers, while in Paris and Brussels there was a coordinated assault in which guns and explosives were employed.

In Nice on 14 July 2016 a truck killed 86 people and injured hundreds, driving at speed through crowds watching a firework display on the Promenade des Anglais until the driver was shot dead by police. Isis claimed that he was answering their “calls to target citizens of coalition nations that fight the Islamic State”. Britain is a member of the coalition with aircraft and special forces troops in action against Isis in Iraq and Syria.

Isis claimed responsibility for a lorry which drove into a Christmas market in 19 December 2016, killing 12 and injuring dozens. As with Nice, this appears to resemble what happened on Westminster Bridge, going by first reports.

The overall location of the attacks today may be significant and would fit in with the way that Isis normally operates when carrying out such atrocities. This is to act in the centre of capital cities or in large provincial ones in order to ensure 24/7 publicity and maximise the effectiveness of the incident as a demonstration of Isis’s continuing reach and ability to project fear far from its rapidly shrinking core areas in Syria and Iraq.

Isis is sophisticated enough to know that such attacks carried out in news hubs like London or Paris will serve their purposes best. In cases of attack with a knife or a vehicle then Isis would not need to provide more than motivation, though individuals seldom turn out to have acted alone. It may no longer have cells in Europe capable of obtaining fire arms or making bombs.

In pictures: Westminster attack Show all 9 1 /9 In pictures: Westminster attack In pictures: Westminster attack An air ambulance lands after gunfire sounds were heard close to the Palace of Westminster in London PA wire In pictures: Westminster attack MPs wait until the situation is under control in Westminster. 'The alleged assailant was shot by armed police,' David Lidington, leader of the House of Commons, told the house. BBC News In pictures: Westminster attack Crowds gather in Westminster after shooting incident, which police are treating as terror attack BBC News In pictures: Westminster attack Police were also called to an incident on Westminster Bridge nearby AP In pictures: Westminster attack Early reports indicate the car, which mounted the pavement on Westminster Bridge and mowed into around a dozen people, was the same vehicle which then rammed into the railings of the Palace of Westminster, just around the corner Reuters In pictures: Westminster attack Security sources described the suspected assailant as a middle-aged Asian man, who is understood to have left the car before attacking a police officer with a seven-to-eight inch knife PA wire In pictures: Westminster attack Police have asked people to avoid the immediate area to allow emergency services to deal with the ongoing incident AP In pictures: Westminster attack One woman has died and a number of others, including the police officer, have been hurt, according to a junior doctor at St Thomas' Hospital Reuters In pictures: Westminster attack At least three gun shots were heard by those inside Westminster, and proceedings in the House of Commons have been suspended AP

It could be that the attacks were carried out by another group, the most obvious candidate being one of the affiliates of al-Qaeda in Yemen. Syria or elsewhere. On 11 March 2017 Jabhat Fateh al-Sham, formerly Jabhat al-Nusra, the Syrian affiliate of al-Qaeda, carried out two bombing attacks in Damascus, killing 59 people, mostly Shia pilgrims from Iraq visiting holy sites. But the Syrian arm of al-Qaeda, while carrying out suicide bombings against targets in Syria, has previously avoided doing so abroad in order to make itself more diplomatically palatable than Isis.

Could the attacks on Westminster Bridge and in Parliament be linked to the siege of Mosul where Isis has lost the east of the city and half the west since an Iraqi army offensive started on 17 October? Isis has traditionally tried to offset defeats on the battlefield, by terrorist attacks aimed civilians that show they are still very much a force to be feared. The same logic led to the ritual decapitation, drowning and burning of foreign journalists and domestic opponents.