The Dallas gunman who shot and killed five police officers and injured seven others supported armed black militia groups, bringing to light a movement that has thrived in the wake of police shootings in recent years.
The gunman, 25-year-old Micah Xavier Johnson, was linked to black separatist groups including the New Black Panther Party for Self-Defense, the Nation of Islam and the Black Riders Liberation Party.
Before Johnson was killed by a bomb detonated by a police robot, he told negotiators he wanted to kill white police officers.
He also told police he acted alone and was not affiliated with any groups.
However, Johnson's online presence has revealed his enthusiasm for black separatist groups.
Though his affiliation with these groups is unclear, his Facebook profile photograph featured him raising a fist in salute to "black power", which is associated with the Black Panther Party movement, a radical political organisation that came to power in response to the 1960s US civil rights upheaval.
He also joined groups online that reference the Black Panther Party,
However, Johnson was reportedly "blacklisted" from many of the organisations that inspired him, the Daily Beast reported.
What are black separatist groups?
While activist groups such as Black Lives Matter have taken a central role in the US movement on police reform and racial justice, black separatist groups have used a more racist and militant approach.
Many black separatist "hate groups" are rooted in racism and anti-Semitism, according to the Southern Poverty Law Center's Heidi Beirich.
Ms Beirich tells the BBC these type of hate groups are different from typical white supremacy groups like the Klu Klux Klan, in that they are formed in reaction to societal white oppression.
Many of today's groups make reference to the original Black Panther Party, which carried out armed citizens' patrols to monitor police behaviour in California during the 1960s.
However, none are affiliated with the Black Panthers.
Who are they?
The New Black Panther Party for Self-Defense (NBPP), founded in 1989 in Dallas, is one of the major black separatist groups in the US.
The group has a 10-point platform advocating the power to practise self-determination for a "black nation", the release of all black people in prison, an end to police brutality against black people, and a call for all black people to arm themselves for self-defence.
The SPLC and Anti-Defamation League have labelled the NBPP as a hate group "whose leaders have encouraged violence against whites, Jews, and law enforcement officers".
Black Panther co-founder Bobby Seale has called the NBPP's rhetoric "xenophobic" and "absurd".
The Nation of Islam (NOI) was founded in 1930 and is considered the oldest black nationalist group in the US.
While the group provides social service programmes to African American communities, the SLPC and Anti-Defamation League have branded it as a hate group founded in anti-Semitism and racism.
The Huey P Newton Gun Club, named after one of the Black Panthers' founders, was created last year in Dallas to oppose "police terrorism".
The group teaches self-defence and conducts patrols in areas where black men have died at the hands of police.
"Us arming ourselves, we're able to create a culture of being independent from government institutions who do not have our best interest in mind," said Rakem Balogun, a founding member of the gun club.
"When [white people] see us with guns, they see boys in the hood", he told the BBC's Dan Murdoch, "instead of thinking black deacons of defence".
Though Johnson was a member of the Huey P Newtown Gun Club's Facebook group, member Erick Khafre told the Los Angeles Times that he had no affiliation to the club "in any way".
Ms Beirich also notes the gun club is not counted as a SPLC hate group as it does not reinforce racist ideals.
How many are there?
In recent years, the high-profile police shootings of African Americans have fuelled the proliferation of black separatist groups, according to SPLC.
In 2015, US police shot and killed a civilian nearly 1,000 times, according to a year-long Washington Post study.
The deaths of Michael Brown, Eric Garner, Freddie Gray and more recently,Philando Castile and Alton Sterling are also among some of the cases that groups have used as an "organising tool" to illuminate the systemic problem with police racism, Ms Beirich says.
In response, the number of black separatist hate groups has jumped from 113 chapters in 2014 to 180 last year, SLPC reported.
What do they believe?
Each group carries different beliefs in relation to black power and white oppression. However, many black separatist groups are explicitly anti-white and tend to share a mistrust of government, according to Ms Beirich.
Some groups are also anti-Semitic and anti-gay, which could be attributed to rhetoric by the long-standing NOI.
The group's leader, Louis Farrakhan, has long espoused anti-Semitism and homophobic messages.
"These false Jews promote the filth of Hollywood that is seeding the American people and the people of the world and bringing you down in moral strength. … It's the wicked Jews, the false Jews, that are promoting lesbianism, homosexuality", Mr Farrakhan said in 2006.
"The group has left a stain on radical black nationalist movement", Ms Beirich says, noting that many radicals may have started as NOI members and spiralled farther into extremism.