Of course a space force existed.
It is unclear whether Trump, who has demonstrated a lack of knowledge about a wide variety of government agencies and programs, knew before he began talking about a space force that the Air Force Space Command has been performing that same mission since it was created during the Reagan administration in 1982.
Here they are below is there website where they tell us their mission statement
"Provide resilient and affordable space capabilities for the Air Force, Joint Force and the Nation" that they have "26,000 space professionals worldwide"
Then they list their existing organization
"Fourteenth Air Force is located at Vandenberg AFB, Calif., and provides space capabilities for the joint fight through the operational missions of spacelift; position, navigation and timing; satellite communications; missile warning and space control.
The Space and Missile Systems Center at Los Angeles AFB, Calif., designs and acquires all Air Force and most Department of Defense space systems. It oversees launches, completes on-orbit checkouts and then turns systems over to user agencies.
It supports the Program Executive Office for Space on the Global Positioning, Defense Satellite Communications and MILSTAR systems. SMC also supports the Evolved Expendable Launch Vehicle, Defense Meteorological Satellite and Defense Support programs and the Space-Based Infrared System.
AFSPC major installations include: Schriever, Peterson and Buckley Air Force Bases in Colorado; Los Angeles and Vandenberg Air Force Bases in California; and Patrick AFB in Florida. AFSPC manages many smaller installations and geographically separated units in North Dakota, Alaska, Hawaii and across the globe."
So are you now going to look at the US Military's Air Force Space Command website and admit that you were wrong about this, or continue to spread this lie?