Justin Bieber has a theory as to why One Direction chose November 13 as their next album's release date when he'd already called dibs on it for his own: a bit of "strategy."

See, Biebs' Purpose drops the same date as 1D's Made in the A.M. -- and since his date was locked down first, he totally sees it as a deliberate move on the U.K. foursome's part.

"They're not really going on the road much, but we're talking about them right now, so it gives them some promo, right?" Justin said in a radio interview with New Zealand's "Smash! The Edge" late last week. "So, that's probably why they did it."

Most people assumed Bieber's little Snapchat video throwing shade at One Direction about their competitive release date was just a bit of tongue-in-cheek fun ... but maybe he wasn't kidding after all.

"I think it was strategy on their part because my release date was first," said Bieber. "But whatever. It's whatever. It's going to be fun. I'm excited to see what happens."