Republicans have been seeking to actualize the Reagan-era Strategic Defense Initiative (the real "Star Wars") for decades. In theory it would eliminate the nuclear threat and give America unchecked dominance globally. With Bush's withdraw from the ABM Treaty in 2002, the main political barrier was removed, but sufficiently low cost launch to low-earth orbit was not yet available and that was what killed SDI / Brilliant Pebbles in the '90s.
Enter Elon Musk and (CIA handler!) Michael D. Griffin. After going to Russia together to examine ICBM design, Elon decides to take Griffin's suggestion and start a company for low cost ultimately reusable rockets, SpaceX. Griffin soon becomes the NASA administrator (Dick Cheney appoints him) and Griffin proceeds to funnel billions of dollars to SpaceX. He also gives Elon key engineers and expert contacts. Griffin later humblebrags that 85% of SpaceX was funded by him with govt money. Elon and Griffin both frequent the Mars Society and decide that while military work has largely gone out of vogue with younger generations, "going to Mars to save humanity" is more inspiring and they use that to recruit. Elon names his first (surviving) son Griffin right before getting the money.
After getting reusable rockets to work by extending the govt design for the DC-X, Elon proceeds to launch constellations of orbiters around the Earth (Starlink), proving the capability to pull off Brilliant Pebbles. Meanwhile Griffin is appointed as a defense secretary by Trump. Griffin then starts the Space Development Agency
(SDA) and the Space Force. The SDA is clearly the first step in a real Brilliant Pebbles and a true SDI.
Unfortunately just as SpaceX is given initial contracts for Space Development Agency, Biden gets elected. He voted against the original SDI and he also slows down the plans to militarize space. Biden realizes the project is destabilizing and would lead to WWIII and likely flawed at intercepting nuclear weapons. Elon then decides to shed any pretense of being a liberal and goes full def con conservative. He buys Twitter to try to sway the next election and curry favors with Republicans..
And here we are.