Elon Musk has taken another jab at Amazon CEO Jeff Bezos following his announcement about a human settlement on the moon. As has been done before by Musk, the Tesla CEO tweeted his personal thoughts on Bezos’ lunar community, which is a part of his Blue Origin space plans.

As Bezos presented his plans for Blue Origin, he expounded upon the company’s goal to put a “sustained human presence” on the moon. Here, spinning cylinders called O’Neill colonies would be placed on the moon, allowing trillions of people to live in the colonies or cylinders with gravity in place, Business Insider reported.

When Musk was asked by a Twitter commenter what he thought of the plans that Bezos is proposing, the Tesla CEO took the opportunity to throw some shade at the idea. Musk said in his tweeted response, “Makes no sense. In order to grow the colony, you’d have to transport vast amounts of mass from planets/moons/asteroids. Would be like trying to build the USA in the middle of the Atlantic Ocean!”

Musk has been quick to come at Bezos in a playful rivalry in the past that has had him calling the Amazon CEO a “copy” with a cat emoji in a tweet when he announced his plans to put satellites into space to provide internet access to remote regions of the world – something that Musk’s SpaceX program also has in the works.

In another instance, Musk poked fun at Bezo’s moon lander named Blue Moon. He sent a round of tweets about the lander’s moniker saying, “putting the word ‘Blue’ on a ball is questionable branding.”

Musk also went as far as to mock Bezos in a tweet about the Blue Moon lander by saying, “Oh stop teasing, Jeff.” Musk accompanied the tweet with an altered photo that read “Blue Balls” on it instead of Blue Moon.

Elon Musk Crew Dragon
Elon Musk's Crew Dragon could play a critical role in turning space hotels into reality. Pictured: Elon Musk, co-founder and chief executive officer of Tesla Inc., speaks during an unveiling event for the Boring Co. Hawthorne test tunnel in Hawthorne, California, U.S., on Tuesday, Dec. 18, 2018. Robyn Beck/Getty Images