Japanese Admiral Isoroku Yamamoto — "You cannot invade the mainland United States. There would be a rifle behind every blade of grass."
Actually, that was Tojo who said that. Yamamoto was supposed to have said, “I fear we have awaked a sleeping giant, and filled him with a terrible resolve.”
Yamamoto’s observation was probably based on Japan’s experience in China. There was a domestic small arms industry due to embargo and warlords needing weapons, and guerilla warfare killed tens of thousands of Japs.
Yamamoto also knew America well and no doubt regarded the nation as awash in guns.
Nowadays he might observe “there will be a pistol in every citizen’s pocket. Occupation will be a very hazardous undertaking for our soldiers.”