For the first time since it was formed after the 9/11 attacks, the Department of Homeland Security is adding white supremacist violence to its list of priority threats in a revised counterterrorism strategy issued Friday.

"The continuing menace of racially based violent extremism, particularly white supremacist extremism, is an abhorrent affront to our nation, the struggle and unity of its diverse population, and the core values of both our society and our department," said Kevin McAleenan, the acting Homeland secretary, in a speech at the Brookings Institute in Washington.

DHS is stepping up its focus on what McAleenan called "targeted violence," in which an attacker selects the target in advance, driven by hate. Racism and anti-Semitism have fueled recent attacks on African-American churches, synagogues, and public places in California and Texas, he said.

The shooting at the Walmart in El Paso hit DHS particularly hard. Six of the victims were family members of DHS employees.

"The majority of our El Paso team, working to protect our nation, uphold the rule of law, and care for vulnerable migrants arriving at our border is Hispanic," he said.

While protecting the nation from foreign-inspired or directed terror attacks remains a core Homeland Security mission, McAleenan said recent mass shootings have "galvanized the Department of Homeland Security to expand its counterterrorism mission focus beyond terrorists operating aboard, to include those radicalized to violence within our borders by violent extremists of any ideology."

The revised strategy said DHS would seek to better analyze the nature and extent of the domestic terror threat and share information with local law enforcement to help prevent attacks. The government will also do more to discourage technology companies from hosting websites that spread radical hate.

Members of the National Socialist Movement hold a rally in Newnan, Georgia, on April 21, 2018. Spencer Platt / Getty Images file

DHS will also encourage counter-messaging campaigns "seeking to steer individuals away from messages of violence," according to the new strategy document. And DHS will provide more active shooter training to local law enforcement agencies to help them respond to gun violence.

Concern about the domestic terrorist threat peaked in the 1990s after the bombing of the Oklahoma City federal building, with a focus on what was called "patriot groups.” That was quickly overshadowed by the threat of foreign terrorism after the 9/11 suicide-airplane attacks.

But according to the FBI, more people have been killed in the U.S. by domestic terrorists in the past few years than by attacks committed or motivated by foreign ones. More domestic than foreign terror suspects have been arrested as well. FBI Director Chris Wray recently told Congress that the majority of the domestic terror attacks are racially motivated, mostly by white supremacists.

McAleenan said countering the extremist message online is an especially important goal.

"It's too easy to get validation for your ideology."