An iconic scene in Stanley Kubrick’s film “2001: A Space Odyssey” shows one of our ape ancestors discovering that a skeleton’s thigh bone can serve as a new kind of tool — a weapon.

The eureka moment is full of unmitigated primal brutality: the ape uses the bone to smash the rest of the skeleton to bits and, later, to bludgeon a less-evolved rival who shows up to a bone fight with nothing more than threatening grunts and flailing arms. The murdered ape’s allies run for their lives, having no doubt learned a lesson. The arms race had begun.

In the real world, the race has brought us to the nuclear suicide pact known as “mutually assured destruction” and to a bully with the nuclear launch codes, President Donald Trump. Show him a bone and he’ll want to wield it.

This month, his administration gave in to Trump’s wishes for a sixth branch of the military and unveiled what it’s calling “Space Force,” a “space warfighting” military plan. Trump endorsed it with the excitement of a child unwrapping a new “Star Wars” toy, tweeting: “Space Force all the way!”

The toy analogy isn’t completely facetious. Shortly after the announcement, Trump’s re-election campaign manager, Brad Parscale, notified supporters in a letter that they’ll soon be able to buy Space Force merchandise. They’ll also get a chance to vote on which of six Space Force logos will emblazon the T-shirts, spaceships, lightsabers or whatever the campaign might have in mind.

Details are sketchy, as with most things coming from the attention-challenged president. Space Force would be a new military force, alongside the Army, Navy, Air Force, Marine Corps and the Coast Guard. The force would develop “space warfighting operations to protect U.S. national interests,” according to a Pentagon report. What that means is anyone’s guess.

Also unknown is the cost; deputy defense secretary Pat Shanahan estimated the price tag at “billions of dollars.” And given how easily the military spends money, and the cost of anything related to space that might just about cover the uniforms.

Less than a year ago, Defense Secretary Jim Mattis was opposed to this ridiculous idea. Setting up a space force, he argued, would increase bureaucracy at a time when streamlining operations and integrating war-fighting among the existing military branches was the priority. But Trump is nothing if not bullheaded. The more he’s told no, the more he charges on. And 10 days ago Mattis did an about-face, and the vice president unveiled the big plans.

One hopes Congress at least — which refused to fund a space force last year — sticks to its guns.