The UK stands "shoulder to shoulder" with France, Home Secretary Theresa May said as investigations continued into the terrorists responsible for the rampage in Paris.
Security in the UK has been beefed up, with an increased presence by police and border staff following the attack in the French capital which killed at least 129 people.
Mrs May said the procedures included "tried and tested" measures for the military to support the police in counter-terrorist operations.
A "handful" of Britons are feared to be among the dead after gunmen and bombers rampaged across Paris, carrying out the worst terrorist attack in Europe for more than a decade.
The first British fatality was named as Nick Alexander, who was selling merchandise for rock band Eagles of Death Metal when their concert was targeted by members of the Islamic State (IS) terror cell thought to be behind the attacks in the French capital.
"British nationals have been caught up in this as well as French nationals. We stand absolutely shoulder to shoulder with the French in relation to this issue," Mrs May told BBC 1's Andrew Marr Show.
"I think we are both very clear that the terrorists will not win, we will defeat them."
The attack aimed at inflicting mass casualties has been seen as a sign the threat posed by IS - also known as Isil, Isis and Daesh - is "evolving" and Mrs May said a review of the security response was taking place.
Mrs May said: "What we have seen from Daesh is that in the past there has been a focus on individuals conducting attacks, being encouraged to conduct attacks.
"What we have seen from the attack in Paris was a co-ordinated attack, a planned attack on a larger scale."
She said the police and emergency services had prepared for a marauding attack by gunmen since the Mumbai assault in 2008.
But she added: "As a result of what has happened in Paris, we will now review that and see if there are any lessons to be learned."
Reports suggest that special forces including the SAS are ready to support counter-terrorism operations on British streets.
Mrs May said: "What we have done over the years since the Mumbai attack is ensure that we have the capability, our police have the capability, they have changed their training so that they can go and deal with these incidents.
"There are tried and tested arrangements in place to provide military support.
"I don't comment on the particulars of any deployments that have been made but we have arrangements in place, where necessary, for the police to have military support."