Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. He is the author of "United States of Jihad: Investigating America's Homegrown Terrorists." David Sterman is a senior policy analyst at New America. The opinions expressed in this commentary are their own. View more opinion articles at CNN.

(CNN)The Trump administration's National Counterterrorism Strategy correctly states that the country has "long faced a persistent security threat from domestic terrorists who are not motivated by a radical Islamist ideology but are instead motivated by other forms of violent extremism."

Saturday's attack in El Paso, Texas, which is being treated as a case of domestic terrorism by federal authorities, according to the US attorney for the Western District of Texas, is a reminder of that long history and its particular threat today.

To prevent future attacks, the United States will need to expand on the work being done by law enforcement to combat right-wing terrorism, and President Donald Trump will need to recognize that the threat posed by far-right terrorists is of a similar scope to that posed by jihadist terrorists.

Trump should also use the bully pulpit of his presidency to attack the ideological underpinnings of right-wing violence rather than stoking its flames.

On Saturday, authorities say, a 21-year-old white man shot and killed 20 people at a Walmart in El Paso, Texas. Minutes before the attack, police say, they believe the shooter posted a "manifesto" on 8chan, an online message board often featuring racist postings, about his support for the terrorist who killed 50 worshippers at two mosques in Christchurch, New Zealand, in March.

Just as school shooters learn from other school shooters, terrorists learn from other terrorists. Notably, the terrorist who carried out the Christchurch attack had posted a manifesto to 8chan just before he carried out the attacks at the mosques.

The latest online manifesto -- a four-page document -- referred to a "Hispanic invasion" of Texas as the rationale for an imminent terrorist attack in El Paso.

Trump has also described immigrants coming across the southern border as an "invasion." However, the writer of the document says his views about immigrants predated Trump becoming president.

The attack in El Paso, if the investigation proves it to be the work of a white nationalist, would be far from the only lethal far-right attack in recent years. Since 9/11, terrorists motivated by far-right ideology, including white supremacy, anti-government and anti-abortion views, have killed 107 people in the United States, according to New America's research. Meanwhile, jihadist militants have killed 104 people in the United States since those attacks.

In other words, far-right terrorists have killed similar numbers as jihadist terrorists have in the United States in the past 18 years.

Additionally, according to New America's data, most far-right terrorist attacks since 9/11 have killed relatively small numbers of people. In the past two years, however, terrorists inspired by far-right ideology have been carrying out mass-casualty attacks. And, if it's confirmed that far-right ideology was behind the attack in El Paso, it is the most lethal far-right terrorist attack in the post-9/11 period.

Less than a year ago, a shooter who was inspired by anti-immigrant conspiracies killed 11 people at a synagogue in Pittsburgh, the deadliest attack against Jews in American history.

Across a wide spectrum of ideologies and beliefs, terrorist violence is rising in the United States. Terrorists inspired by ideological misogyny have, for instance, killed eight people in the United States in recent years. One shooter killed six in Isla Vista, California, in 2014 in attacks he framed in terms of his hatred for women. And last year, a gunman killed two women at a yoga studio in Tallahassee, Florida, using the same rationale. Similarly, individuals inspired by black nationalist ideology have killed eight people in the United States in the past three years.

Meanwhile, since 9/11, no foreign terrorist organization has carried out a deadly attack in the United States. Every one of the perpetrators of the 13 deadly jihadist attacks that have killed 104 people in the United States since 9/11 was a US citizen or legal permanent resident.

Yet the Trump administration continues to fail to recognize the true nature of the terrorist threat in the United States. Its answer to terrorism was suspending travel from largely Muslim countries that would not have stopped a single deadly terrorist attack since 9/11.

To its credit, law enforcement is investigating far-right terrorist threats. According to FBI Director Christopher Wray, there have been about 100 domestic-terrorism-related arrests this year.

That said, more needs to be done, as underlined by the statement on Sunday from six of the nation's top former counterterrorism officials who served under Presidents George W. Bush, Barack Obama and Trump. It reads, "it has become abundantly clear over many months now that more must be done to address acts of violence driven by extremist views of all types, including acts of domestic terrorism. We call on our government to make addressing this form of terrorism as high a priority as countering international terrorism has become since 9/11. ... We simply cannot wait any longer." Indeed.