The billionaire founder of Tesla and SpaceX likes the idea of an agency that provides “defense in space,” noting that the world might follow US President Donald Trump’s example and introduce their own space military departments as well.

Musk gave his comments as a part of an interview with Kara Swisher on the Recode Decode podcast Friday. The visionary behind SpaceX said he found the idea of the Space Force “a little controversial,” yet he thought it was “cool.”

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“You know, like, when the Air Force was formed, there was a lot of, like, pooh-poohing, and, like, ‘Oh, how silly to have an Air Force!’ People today may not realize, back then it was widely panned as a ridiculous thing to create the Air Force, but now everyone’s, like, ‘Obviously, you should have an air force.’ I think it’s gonna become obvious that we should have a space force too,” Musk said.

He also told Swisher that the Space Force could become helpful in the future expansion of Earth’s civilization into space, suggesting the possibility of building Space Force bases on the Moon or on Mars.

“Anyone who has an exploratory spirit — and I think that especially applies to a country like the United States, where, you know, it’s kind of the distillation of the spirit of human exploration — I think the idea of being out there among the stars and among the planets is very exciting,” he added.

Trump announced he was planning to ask the Department of Defense and the Pentagon to establish a Space Force during the National Space Council meeting back in June. The Space Force is poised to become the sixth branch of the US armed forces if Congress appropriates funding for it.

“When it comes to defending America, it is not enough to merely have an American presence in space. We must have American dominance in space,” Trump said, noting that the Air Force and the Space Force will be “separate but equal” branches of the military. US Air Force military officials in September argued that the creation of such department would be a drain on resources, with an estimated cost of almost $13 billion.