Speaking to reporters, Harden explained that he chose the mask "because it covered my whole beard. ... It covered my whole beard, I thought it looked cool, that was it."
The Rockets tweeted out a picture of Harden with the caption "Mask Up" on Thursday:
The image prompted an assortment of reactions from social media. Singer Trey Songz called it "certified clown s--t" on Twitter.
Rapper Young Thug tweeted that Harden "don't have internet so he obviously don't know what's right or wrong if he posted something that's against US."
Per Tim Elfrink of the Washington Post, the "Thin Blue Line" mask that Harden was wearing is considered "a pro-police symbol that critics have long claimed also stands for white supremacy and opposition to the Black Lives Matter movement."
Harden has spoken out in support of the Black Lives Matter movement that has continued to grow in the aftermath of George Floyd's killing while in Minneapolis police custody May 25.
He said during a Zoom press conference Thursday "it was amazing" how the city of Houston rallied and "so many people could come together" for a specific cause amid protests against police brutality and racial injustice.