I think the operative word here is "small".

In 1939, Germany, a country, in area and population, much larger than England, was invading smaller, weaker, neighbouring states.

When we, backing the USA, decided to invade Iraq, we were the invaders of a smaller weaker state.

Inevitably the perspective changes, and the two are viewed as almost mirror images.

I'm not sure how Vietnam fits into this scenario though, since I understood that the USA were invited in by the South Vietnamese government, to help fight off invasion from the North, backed by Communist China.

Perhaps someone with more intimate knowledge could enlighten me.

Don T.