Donald Trump thinks America needs a new division of the military called the "Space Force."

"My new national strategy for space recognizes that space is a war-fighting domain, just like the land, air and sea," he said during a visit to San Diego on Tuesday. "We may even have a Space Force. Develop another one. We have the Air Force, we'll have the Space Force."

It sounds like a joke, and Trump even admitted that the idea began just days ago when he threw out an idea that "was not really serious."

"You know, I was saying it the other day, because we're doing a tremendous amount of work in space. I said, 'Maybe we need a new force. We'll call it the Space Force. And I was not really serious. And then I said, 'What a great idea, maybe we'll have to do that.' It could happen."​

At this point in Trump's presidency, long-accepted norms about presidential behavior and common sense have been thrown out the window. But he manages to keep saying things so baffling and simplistic, that they still surprise us.

Earlier in the day, while looking at prototypes for a new border wall, Trump told reporters"Getting over the top is easy. These are like professional mountain climbers—incredible climbers. They can't climb some of these walls. Some of them they can. Those are the walls we're not using."​

Trump also seemed set on the idea of finding a wall that he can see through.

"You have to know what's on the other side of the wall," he said. "You could be two feet away from a criminal cartel and don't even know they're there. Now we have equipment to take care of that, X-ray equipment, et cetera."

​Since his campaign, Trump's promise of a "beautiful and massive" wall paid for by Mexico has become a punchline for his critics. In San Diego, the president was met by protesters and explained his doomsday fears of a country without a big wall: "For those people, if you don't have a wall system, we're not going to have a country. They have the cartels, fighting the cartels. Nobody ever fought them like we fight them. We fight them hard. It would be bedlam, I imagine."

A 2017 report from the New York Times revealed that the wall could cost nearly $70 billion to build and $150 million a year to maintain.