I have always just presumed so... :chin:

Well, Red Skull and Captain America took the same drugs, so maybe they were having raves together or something?

There's some story in the comics where it turned out that Captain America was actually a Hydra operative all along, and therefore had been implicitly a Nazi back when Hydra were Nazis. That was apparently horrible unpopular with fans, and I'm not sure if it's been retconned or was always an alternate universe or what. There's a nod to it in Endgame that seemed to make a lot of people happy though, where [spoiler]Captain America pretends to be an undercover Hydra agent to get something from actual Hydra agents)[/spoiler].

There's some story in the comics where it turned out that Captain America was actually a Hydra operative all along, and therefore had been implicitly a Nazi back when Hydra were Nazis. That was apparently horrible unpopular with fans, and I'm not sure if it's been retconned or was always an alternate universe or what. There's a nod to it in Endgame that seemed to make a lot of people happy though, where [spoiler]Captain America pretends to be an undercover Hydra agent to get something from actual Hydra agents)[/spoiler]. — Pfhorrest

Yep, Project Insight reveals this.