There are calls for political and social unity after the fatal Pittsburgh synagogue shooting which left 11 people dead.

The shooting is being treated as a hate crime after it was reported the 47-year-old gunman shared anti-Semitic comments online, and shouted about killing Jewish people as he entered the synagogue.

The attack has been followed by cries to put out simmering anti-Semitism in the country.

Rabbi Abraham Cooper from Jewish human rights group the Simon Wiesenthal Center told Mike Hosking politics is becoming more and more combative.

"There's no question that our discourse is broken here in America - it's fractured. But we need a new kind of vocabulary that would allow people to debate ideas without demonising the other."

"As far as attitude, so much today in our world is dominated by social media and it's sometimes hard to track how much these ideas carry over to the real world."

He said social media has empowered people to share hate. 

"It allows for the marketing of hate of all sorts including anti-Semitism 24/7. It's not so much the number as it is that the true believers are empowered and validated to hold such views."

"I think we have had a generational shift from the far-right extremists of the 1970s and 1980s, most of which have either died or are out of the picture, and now more internet driven 20 or 30-year-olds."

Cooper said politics are playing a huge part in the hate and aggression plaguing America.

"The leadership needs to come from both parties starting with the President."

US correspondent Richard Arnold told Mike Hosking the shooting is part of an alarming trend.

"Stats show that anti-Semitic incidents here have risen by 57 percent in the past year, including the neo-Nazi march last year in Charlottesville."

He said America is reeling after the attack.

LISTEN ABOVE AS ABRAHAM COOPER SPEAKS WITH MIKE HOSKING