NEW YORK - No one looked up at the sky, as everyone did for months after 9/11, without thinking, every time the sound of a plane engine was heard.

Of course, the New York Police Department went immediately on state of alert, along with city firemen and the National Guard. Ray Kelly, the NYPD commissioner called the 1,000 officers specifically assigned to counter-terrorism. Surveillance of subways and bridges was heightened. CCTV's covering the city, were watched with particular attention, to discern any suspicious move.

But New York did not face a shock similar to the one that came with 9/11.

This time, New Yorkers were spectators, and they did like everyone on social networks: each advocated his or her own theory about the culprits. “Today is the deadline for fiscal declarations, I wouldn't be surprised if an anti-government bastard did it,” ventured one friend on Facebook

Someone else, speaking to the New York Post, wondered if the attack had originally been planned for the New York City Marathon, which was called off because of Hurricane Sandy.

But apart from such chatter, for the New York crowd enjoying a sunny Spring day, Boston seemed far away.

It is not just the distance. That September day in 2001 has deeply changed New York, and the rest of America along with her. The country has been prepared to absorb unpredictable attacks by mass murdering gunmen; and the real surprise is, for many, that the country and the city have not faced any major attack during the past twelve years.

In London and Paris, too

The bewilderment following 9/11 has been replaced by a hardened America, somehow subtly less open and candid. The same goes for London or Paris: there is indeed danger, we live with it.

Barack Obama's masterful statement, projecting his calm resoluteness, was as far as one can travel from that image of George W. Bush, megaphone in hand on the rubble of the World Trade Center. The message to the culprits though is largely the same: whoever you are, we will hunt you down, and punish you. Now it's coming from a President who has already proven it, by eliminating Osama Bin Laden.

Another difference, between Boston 4/15 and New York 9/11 is the pure speed of social networks in defusing the most outrageous fears and least reliable information. For hours, in 2001, New Yorkers expected other planes to fall from the sky. The maddest of rumors were spreading.

Yesterday, word of an attack against the JFK library in Boston was quickly disposed of: it was an accidental fire, nothing to do with any kind of sophisticated, coordinated terrorist strike. New Yorkers, eyes glued to their smart phones, already knew the truth.