The two suspects appear to be Islamists: Tamerlan Tsarnaev, who died in a hail of police bullets on Friday and his younger brother, Dzhokhar, whom the police arrested the same day.

Certainly the two, who as far as we know came from Chechnya, must have lived through terrible experiences in their former home – war and violence that ultimately brought them to America in search of a better life. But, apparently, they never really arrived, never embraced, the open, Western culture of the United States. On the contrary, they used the freedom America offered them, it seems, to perpetrate a horrific crime.

The bomb attacks in Boston have changed America. Of course, people are asking themselves what can be done to prevent something like this from happening again. That the suspects were discovered so quickly has to do with the fact that cameras are installed in public places in US cities. One can now be sure that the number of cameras monitoring public life will rise.

But the most important aspect contributing to the identification of the Chechen brothers was the ubiquitous smartphones owned by practically everyone. It was the photographs that private individuals snapped and passed on to police that put the FBI on the trail of the suspects. Without the help of ordinary people it would have been more difficult and time-consuming for the security forces to track down the leads.

This revelation has sensitized Americans all over the country. Their involvement, their alertness, is apparently very important when it comes to public safety. This realization has led to people accepting far-reaching restrictions on their freedom; something that was unthinkable before the attacks of September 11, 2001.

At the moment, the residents of Boston and Watertown are glad that the suspected terrorists have been killed or captured. Huge crowds of people flooded the streets in the middle of the night to celebrate boisterously. For the time being, at least, they have forgotten the mundane and all too obvious insight that in an open society there can never be perfect security.