The US Regular Army (RA) was founded in 1775. State militias supported the RA through the various wars fought on what is now US soil (including the Revolutionary War and the War of 1812). In the Civil War, the RA was supported by volunteers and fought on the side that ultimately won. The Confederate Army was similar to the RA at the time. Currently, the RA has been absorbed into the US Army (including Army Reserve and National Guard).
Source: https://en.wikipedia.org/wiki/Regular_Army_(United_States) and https://en.wikipedia.org/wiki/History_of_the_United_States_Army
So… yes there was a federal military, but it was a different thing than the US Army is now. How that would play out if things went bonkers in 2025… who knows. There are a LOT of people around the world watching VERY closely though… and really hoping (not that confidently though) that sanity will prevail.
Yes… but what colour?