Suspicion and fear after California attack plays into the hands of partisan politics

Something appears to be changing in America.

That sunny outlook, that sense of hope, that openness, is under assault since the San Bernardino massacre.

Ronald Reagan captured the old American sentiment when he used to declare that "a stranger is a friend I haven't yet met."

That's not the mood at the moment.

It wasn't the numbers of those killed and injured. 14 killed, 21 injured is not exceptional by the ghastly standards of US mass shootings.

But it was the nature of the attack - suburban, self-radicalised extremists living under the radar. Worse than that, Farook and Malik were living their small slice of the American Dream.

He had a good job and was respected. They had a young baby together, a nice home in a respectable neighbourhood.

So for many Americans, the attack threatens the whole uplifting idea of assimilation and integration that is at the heart of society here.

There is also the feeling that if a Christmas gathering of environmental health workers - of all things - can be targeted, well, everything is a potential target.

I spoke to neighbours of Farook's who told me that - reluctantly, regrettably - they were now looking with suspicion at other immigrant families. They had lost their sense of trust in others.

And here's the danger: it is playing into the fiercely partisan politics of the 2016 Presidential campaign. Republican candidates are already using incendiary and polarising language to describe the "Muslim threat from within."

So it is no wonder that America's Muslim population is feeling vulnerable. Islamophobia is on the rise. And the backlash may have only just begun.