Twitter on Monday briefly suspended the account of David Duke, a former leader in the Ku Klux Klan.

Twitter users attempting to view Duke's tweets Monday morning were instead greeted with a message that his account had been suspended. It wasn't immediately clear what prompted the move, but Duke's account was reinstated after just a few hours.

Duke, a former imperial wizard in the white supremacist group, tweeted his return to Twitter, saying he didn't know the reason for his account's suspension.

Twitter representatives did not immediately respond to a request for comment.

The social network has for years struggled with how to combat abusive and harassing behavior on the platform. In December, Twitter suspended the account of Richard Spencer, a white nationalists who advocates a separate white homeland, at the same time as a handful of accounts that targeted black and Jewish people were closed. Spencer's account was reinstated after a nearly month-long absence after he designated it as his official account.

Twitter has also permanently banned ultra-conservative journalist and former Breitbart editor Milo Yiannopoulos, one of the principals accused of launching the abuse campaign last year against actress-comedian Leslie Jones.

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