The New American Foundation, a reliable centrist source on national security, parses 20 years of data.
the attacks are not national catastrophes of the type the United States experienced on 9/11. Instead the death toll has been quite similar to other forms of political—and even non-political—violence Americans face today.
The data suggests America’s fast growing terror threat comes from domestic right-wing radicals, not from violent Islamists.
Source: What is the Threat to the United States Today?
