London will ‘never be cowed’

and a police officer whom he stabbed.

The attack was the most serious in London since the Underground bombings of July 2005. It follows murderous attacks more recently in other European cities, notably Paris, Nice, Berlin and Brussels.

The latest attack was not unexpected. The international terrorism alert level in the United Kingdom before Thursday’s events was already at ‘‘severe’’, and had been since August 2014.

It is too early in the investigation to be sure, but this latest outrage had the hallmarks of a lone-wolf attack, involving the use of a vehicle to ram innocent people and knives as weapons. Such methods enable a radicalised individual to cause mayhem without tactical training, or access to firearms or explosives.

Terrorist organisations such as Isis have called for supporters to stage such lone-wolf operations as a way of causing distress globally at little cost to themselves. They are difficult to forestall, because a single person acting alone and using whatever is at hand is more unpredictable and more difficult to detect than groups or networks of people conducting planned operations with logistical backup.

The idea that a lone attacker can strike, seemingly at random, is in itself a cause for worry and concern. It should be remembered, however, that killing people is not the main driver of this sort of terrorism. The real objective is to spread fear and disunity.

Londoners have shown that, collectively, they are not easily frightened. A previous generation of the city’s inhabitants withstood nearly two months of continual bombing during the Blitz of World War II, and strived to carry on regardless.

Since then, attacks were carried out in London through the latter 20th century by anarchists, Palestinian groups and, notably, the Provisional Irish Republican Army. With each incident, the city recovered and moved on. In fact, London has witnessed far fewer attacks in the 21st century than at the height of the IRA campaign.

And when terrorism occurs, the true face of humanity appears. It can be seen in the rush of people to help the wounded, and in the vain attempts to resuscitate not just the felled policeman but also the shot terrorist in the Palace of Westminster yard.