PARIS: The men and women involved with antiterrorism here have a reputation of being among the best in Europe.
One of the reasons for their expertise in the age of jihad is that they have been confronting Islamic extremism longer than most European countries.
While Britain was concentrating on the Irish Republican Army, and Spain on Basque separatists of the Euskadi ta Askatasuna, the French were involved with after-effects of their North African empire.
And few countries in the world have witnessed more Islamist violence than Algeria, over which France fought a long, colonial war before it gave in and accepted Algerian independence.
Although Islamists from every country can be found in France, it is from North Africa that most of France's antiterrorism worries come.
European imperialism that ended in the last century has had its blowback effect as the former colonized flood into the space of the former colonizers. They crowd into the despairing suburbs, hoping to better their lives in a European dream that constantly eludes them.
"We keep strong relationships with former colonies," said a French official. "We have the most intimate relationships, but they are complicated. Love and hate. And, unfortunately, some who live here feel discriminated against - racism."
Antiterrorism authorities here are known for their capacity to infiltrate potentially unfriendly organizations in order to monitor them. They have a much higher number of people versed in foreign languages and cultures than their American counterparts.
When it comes to home-grown Islamic threats, of the kind that bombed the London subway, "in France we have better control over our domestic situation than do our British friends," an official told me.
"We also have tools, legal weapons, that are unlike others in the Western world," said another.
The French authorities also have powers of surveillance and communications intercepts that would make even Dick Cheney blush.
The sharpest tool in the French antiterrorist arsenal is a law, unique in the French legal system, that makes "an intention to commit a crime a crime itself," an official explained.
It sounds a bit like the American RICO laws, which have been used successfully against gangsters. "We use it carefully so we don't get the European Union human-rights courts on our neck," he said.
The trick is to create "very close relationships between intelligence and law enforcement activity, and by prosecuting defendants for conspiracy. I believe it is easier to charge someone with conspiracy in France than in the United States."
The French pay a great deal of attention to what one policeman called the "genealogy" of terror - the grievances, the links, the associations of radicalism, the funding connections. There are increasing efforts in Europe to build bridges to other legal systems in Europe.
I found my sources here perhaps more philosophical than their counterparts elsewhere.
There is an understanding that, although modernization - better education and living conditions to lift people out of poverty and ignorance - can help with Islamic radicalism in the long run, there is also an inevitable backlash against modernization itself.
Modernization can create its own fear, especially in the Muslim world where the new can seem a threat to religion.
There is a human tendency to react against perceived corruption and decadent idolatry.
There may be a direct link between the reaction of Moses to the golden calf, the proclamations of Martin Luther nailed to the church door, and the election of Hamas in Gaza, which was a reaction against the corrupt ways of Fatah.
But understanding why people might turn to terrorism is only part of the puzzle of how to prevent it.
The French legal system tries to "avoid legal overreactions which can be criticized from a legal point of view," according to one judge, but at the same time be effective in combating terror.
"We know we are succeeding in blocking several terrorist attempts each year," an official said, "but one day we know we will be unlucky. Unfortunately it is a probability."