NBA commissioner Adam Silver told ESPN on Sunday that president Donald Trump’s alleged disparaging comment about Haiti and unnamed African nations are “discouraging” but vowed the league would “continue pushing forward” with efforts to combat social injustice.

“Sports continue to be a unique opportunity to unite people and it is a place where there is a rare sense of equality,” Silver said in Memphis on the eve of Martin Luther King Jr. Day, where the Lakers will face the Grizzlies (5:30 ET, TNT). “Certainly we are proud that within the NBA you are judged by your performance on the floor, regardless of your background, nationality or ethnicity.

“I tend to be an optimist. Certainly as I am reminded of the history of this country, much of it which took place during my lifetime, there has been tremendous progress, there is no question about it. Having said that, we have a long way to go.”

Trump continued to defend himself on Sunday after allegedly questioning at a recent meeting why the United States should accept immigrants from “s–thole” nations like Haiti. It marked the latest racial controversy for Trump, including reports that he allegedly said Haitians “all have AIDS” and fretted that Nigerians would “never go back to their huts” in Africa if they were allowed to visit the U.S.