President Barack Obama delivered a powerful defense of the Black Lives Matter movement at a panel on criminal justice reform Thursday. He argued that the movement has drawn attention to many of the unique problems that Black communities face in the U.S., including police brutality and mass incarceration.

At the forum, hosted by the Marshall Project, Obama explained how the motto, "black lives matter," was not meant to alienate people but rather to highlight concerns about racial injustice that have long been ignored. For that reason, he argued, "all lives matter" misses the point.

RELATED: Shutting Down the Most Common Attacks on Black Lives Matter

"I think the reason that the organizers used the phrase 'black lives matter' was not because they were suggesting nobody else's life matters. Rather, what they were suggesting was there is a specific problem that is happening in the African-American community that's not happening in other communities. And that is a legitimate issue that we've got to address," he said.

Obama went on to discuss the relationship between race and the criminal justice system, a subject that is at the core of the Black Lives Matter movement and that the president has emphasized in past speeches. He recognized that there are concerns about unfairness in the U.S. justice system—concerns that Black people are disproportionately incarcerated and subjected to excessive force by police.

RELATED: This One Graphic Sums Up the Devastating Racial Disparities in Our Prisons

He said that the data shows that most police in the country have been doing the right thing, performing a tough and important job. That said, "we as a society—particularly given our history—have to take this seriously."

"And one of the ways of avoiding the politics of this and losing the moment is everybody just stepping back for a second and understanding that the African-American community is not just making this up," Obama said. "It's not just something being politicized. It's real, and there's a history behind it. And we have to take it seriously."