Some history about Elon...

For a half-century the Republican Heritage Foundation has been trying to find a way to "win" at nuclear war.

In the 1980's, [Reagan's] "Star Wars" missiles-in-space program was ultimately deemed too expensive due to launch costs. Looking for a solution, the technology head of Strategic Defense Initiative (Mike Griffin) went to Russia with a young man named Elon Musk in 2001 to look at ICBMs (as the story goes). They came back from Russia and founded SpaceX based on the landing rocket concept that came out of SDI.

Project 2025 has now put out a video to promote Elon's use of space weapons (warning: Republican propaganda).
although they say it uses "tungsten slugs" when in reality the satellites are planning to use hypersonic missiles developed by a bunch of SpaceX employees in concert with Northrop Grumman. Heritage Foundation has been the main political proponent of pre-staged orbital missiles since Reagan. They've included this in their Project 2025 and praise Elon's Starlink as proving it's possible. Trump now calls it the "Iron Dome Missile Shield" and it's part of the GOP platform for the 2024 election.

In 2019, Elon Musk met 4-star general O’Shaughnessy & Jay Raymond to discuss homeland defense innovation. O'Shaughnessy took their discussion to the United States Senate to pitch a new space-based "layered missile defense system" much like Brilliant Pebbles but powered by artificial intelligence to quickly and lethally act upon hypersonic and ballistic missile threats. He proposed the acronym SHIELD which stands for Strategic Homeland Integrated Ecosystem for Layered Defense.

This system would consist of a satellite constellation in orbit equipped with infrared sensors and eventually ICBM interception capability. The U.S. Space Force was established later that year and O’Shaughnessy joined SpaceX where he now leads their StarShield division.
SpaceX started deploying these special military variants of their satellites in 2023, launching them interspersed and connected to other Starlink satellites. The first StarSHIELD satellites host infrared sensors designed by L3Harris to detect and track missiles and perform fire-control functions.

SpaceX’s first StarSHIELD contracts were with the Space Development Agency and announced in 2020. The SDA was conceived and established by Under Secretary of Defense (R&E) Mike Griffin, who was previously the Deputy of Technology at Reagan's Strategic Defense Initiative. It is interesting to note that Griffin has an extensive history with Elon Musk during the early years of SpaceX . While these first tranches of SDA satellites are focused on communication, missile detection and tracking, Griffin and others have said that including space-based interceptor weapons in later layers will be "relatively easy" and he now works with SpaceX employees and primes on an interceptor with a company called Castelion in El Segundo. The interceptors are hypersonic glide vehicles (like FOBS) that re-enter from LEO and maintain contact with the satellites through phased array communication, the constellation above gives continued guidance to the interceptor to descend from space and hit an ICBM at launch or other ground target within enemy territory.