In the 14 years since the September 11, 2001 attacks, nearly twice as many Americans have been killed by white supremacists, right-wing extremists, and other non-Muslim domestic terrorists than by people motivated by "jihadist ideology," a report by the New America research group published Wednesday has found.

Using a database that catalogs information on U.S. citizens and permanent residents engaged in "violent extremist activity," the report, Homegrown Extremism 2001-2015, found that 48 people were killed by non-Muslim terrorists during that time frame, as opposed to 26 who were killed by self-described jihadis.

The New York Times reports:

The slaying of nine African-Americans in a Charleston, S.C., church last week, with an avowed white supremacist charged with their murders, was a particularly savage case. But it is only the latest in a string of lethal attacks by people espousing racial hatred, hostility to government and theories such as those of the “sovereign citizen” movement, which denies the legitimacy of most statutory law. The assaults have taken the lives of police officers, members of racial or religious minorities and random civilians.

...John G. Horgan, who studies terrorism at the University of Massachusetts Lowell, said the mismatch between public perceptions and actual cases has become steadily more obvious to scholars.

“There’s an acceptance now of the idea that the threat from jihadi terrorism in the United States has been overblown,” Dr. Horgan said. “And there’s a belief that the threat of right-wing, antigovernment violence has been underestimated.”

Last week's shooting at the Emanuel A.M.E. Church in Charleston, South Carolina, in which nine black men and women were killed, was the deadliest right-wing attack in the U.S. since 2001, the report states. The suspect in the murders, 21-year-old white supremacist Dylann Roof, said he had intended to start a race war through his attack.

But despite these findings, the general public and mainstream media resist the language of "terrorism" when describing so-called homegrown radicals.

As Fairness and Accuracy in Reporting (FAIR) editor Jim Naureckas wrote in a column published on Common Dreams this week, "Corporate media are demonstrably reluctant to use the word 'terrorist' with regards to Charleston shooting suspect Dylann Roof—even though the massacre would seem to meet the legal definition of terrorism, as violent crimes that 'appear to be intended…to intimidate or coerce a civilian population'."

Abdul Cader Asmal, a retired physician and a spokesman for Boston’s Muslim community, told the Times on Wednesday, "With non-Muslims, the media bends over backward to identify some psychological traits that may have pushed them over the edge. Whereas if it’s a Muslim, the assumption is that they must have done it because of their religion."

Roof's attack was "not an act of just 'one hateful person.' It is a manifestation of the racial hatred and white supremacy that continues to pervade our society," wrote University of Pennsylvania professor Anthea Butler in an op-ed for the Washington Post last week, just as Roof was captured by law enforcement. "It should be covered as such. And now that authorities have found their suspect, we should be calling him what he is: a terrorist."