WASHINGTON (AP) — President Donald Trump has demanded that Pentagon create a new military service, a Space Force to assure "American dominance in space." And with that demand, Trump has injected urgency into the debate over the best way to protect U.S. interests in space, both military and commercial.

But his approach has left many struggling to understand basics such as what a Space Force would do and how much it might cost.

The Pentagon is expected to have enough details by early next year to include a Space Force plan in its 2020 budget request.

The idea has taken on a life of its own at Trump's rallies. That's partly due to his conflating of the nation's civilian space program with the military's separate role of providing space-based navigation and communications satellites.