NICK CARTER isn't sure he believes that his younger brother AARON CARTER fought off a bunch of NEW KIDS ON THE BLOCK fans, who had jumped him for being on New Kids' turf.
Aaron had boasted on Twitter, quote, "I'm a 6th degree Black Belt in Muay Thai. They lost."
Nick was asked about Aaron's story in a radio interview . . . and he said he didn't know what happened, but he did have this to say: Quote, "He's not a Black Belt in anything . . . dancing, maybe . . . dance fighting."
He added, quote, "I literally talk to all the New Kids all the time, and we've got a past in this town with these guys. So Aaron started associating with us in that way.
"It's just a little strange . . . the whole situation went down. But you know, it's my brother. He's young. I was young one time."