They all underwent alterations during the Red Scare. The New York Times, in a story reporting comic book Superman giving up his U.S. citizenship, adds this correction:

An earlier version of this blog post misstated the mission of Superman when the comic book began in 1938. He fought for truth and justice but not the American way, a goal that was added when the television show had its debut in the early 1950s.

I guess just truth and justice sounded a little pinko.