A guidance note from the UK CPNI (Centre for the Protection of National Infrastructure) has been published, giving advice and guidance on what organizations can do to protect sites from terrorism.
The guidance points out that “whilst it is inherently difficult to protect against this [Paris] style of attack in open, public places, there are some pragmatic, low cost security measures that can be rapidly utilised to enhance security of a site.”
It also states that the Paris attacks perpetrators are likely to have conducted hostile reconnaissance, the information gathering phase that is a vital component of the attack planning process. If you can disrupt hostile reconnaissance, you can help reduce your
vulnerability to attack, says CPNI. While in open crowded places, it may not be possible to deny access to public areas, measures can be rapidly put in place, or existing capabilities enhanced to help disrupt hostiles by detecting and deterring them.