He said the two had had a "constructive exchange" by phone, though did not say whether Trump had made any demands regarding possible talks with Russia.

"People need to find different strategies or constructive ways to deal with their emotions… making them less likely to react violently in moments of intense emotional stress."

He has done an awful lot of constructive — there have to be limits to the disruptiveness if you are going to get anything done in the world .

"As a demographer, I don't think states should be overly concerned about these issues. They can be resolved through constructive negotiations between federal and state governments," says Mr Goli.

Without a constructive response, their alienation and resentment will continue to grow, fueling further polarization and violence.