RE: An American with a gun behind every blade of grass; Admiral Yammamoto
Apparently, there is no proof that this was ever said by Yamamoto.
However, it should be noted that Yamamoto spent time in the U.S., attending Harvard for two or more years. He spoke fluent English and had a keen understanding of the industrial capabilities of the United States. He did not want war with the U.S. for this, and possibly other reason.
Therefore, while he may not have made this now-famous quote, it is likely that he may have believed it, therefore being a good person to attribute it to.
I’m also unsure about this line that was attributed to Yamamoto, quoted in the movie TORA, TORA, TORA ( afer Pearl Harbor was bombed):
“I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve.”
What Yamamoto feared most was America’s industrial capacity.
He also feared that Japanese arrogance & sense of superiority over the hated `gaijin’ would prove to be Japan’s undoing.