There has been a striking visual image of increased security after the attack on satirical newspaper Charlie Hebdo in Paris.
In France, it was seeing 10,000 troops on the streets, said to be for civilian protection.
Then there are the less visible measures, being discussed behind the scenes.
In the case of the British prime minister, that means gaining access to online chatter. Responding to the Paris attacks, David Cameron said there should be no means of communication which the government cannot read.
Cameron wants new laws that would allow security services to read encrypted communications sent by members of the public on apps such as Apple's iMessage or Facebook's WhatsApp - the sort of digital communication he says could be used by suspected terrorists.
Speaking on Monday Cameron said: "The next government - and I hope it's a government I lead - will have to legislate again in 2016 and what I can say is that if I'm prime minister, I will make sure it is a comprehensive piece of legislation that makes sure we do not allow terrorists safe space to communicate with each other."
So, can governments strike a balance between security and personal privacy? And is Cameron’s proposed law a justified response to the Paris shooting or an unnecessary overreaction?
Presenter: Adrian Finighan
Justin Crump - a risk analyst and security and intelligence specialist
Sara Ogilvie - a policy officer at the human rights group, Liberty
Nino Kader - a technology specialist and social media commentator
Source: Al Jazeera