The attack on Parliament in London is another reminder that a facility's security is only as strong as its weakest point. In this case, it was a frequently used gate in New Palace Yard that was left unlocked. Known as Carriage Gates, the entrance is generally monitored by police officers. Could the weakness have led to the attack? Could the attack have been prevented (or minimised) if the gate had been bolted shut?

Planned ‘complete security overhaul’

Finger pointing in the wake of such incidents may seem counterproductive, but there is value in assessing any lessons learned. Reports of a planned "complete security overhaul" in the wake of the London attack make sense. In any case, the existing security procedures likely minimised the impact of the attack, which could have been even worse and more deadly.

As it was, a terrorist drove a vehicle down a Westminster Bridge pavement crowded with pedestrians and into a perimeter fence. Getting out of the car, the man stabbed the first officer he encountered after entering the unlocked gate; the officer later died of his wounds. Five people were killed, including the attacker, who was shot to death. Twenty-nine were wounded, including seven reported in critical condition.

The low-tech, rudimentary nature of the attack is another reminder of the changing face of terrorism

The changing face of terrorism

The low-tech, rudimentary nature of the attack is another reminder of the changing face of terrorism. Previous emphasis on elaborate, carefully planned attacks seems to have given way to a more barebones approach to creating terror: Simply drive a vehicle into a crowd of people. Planning more elaborate attacks tends to involve more people and could leave an electronic trail to enable security and anti-terrorism agencies to uncover plots before they can be carried out. In contrast, driving a vehicle into a crowd is easier, might involve fewer perpetrators and likely needs little advanced planning.

Successful detection of more elaborate plots has led terrorism groups to resort to the simpler route. Several terrorist-related web sites have reportedly encouraged followers to use vehicles as weapons of terrorism. ISIS has claimed responsibility for the London attack. The plan was simple and almost undetectable until it happened.

Vehicle barriers

Vehicle barriers can help prevent such attacks, whether concrete or moveable bollards, steel fencing, crash-rated portable barriers, or other measures. They are currently used all over the world, including government buildings and high-profile locales where pedestrians might gather.

The Elysee Palace is fortified by high walls and steel fences
and is restricted from traffic
and protected by armed patrols

For example, Berlin's Reichstag has fences in front of the building's main entrance and is surrounded by low concrete blocks, although it is largely accessible to the public with no fences on the other sides. The European Parliament headquarters in Brussels is protected by low steel bollards on the roadside, and the French National Assembly's front gates are protected by concrete bollards to prevent high-speed ramming. France's Elysee Palace is fortified by high walls and steel fences, and is restricted from traffic and protected by armed patrols. Vehicle traffic around the Capitol building in Washington, D.C., is restricted; steel railings several feet high, also encircled by steel bollards and chains, protect the perimeter of the White House.

Such venues will be the subject of new security evaluations, even as Britons look for answers about how the latest attack could have been prevented. The challenge is that any weak spot could be the point of entry for the next tragedy.