He was trying to tap into the idea that Japan is a country that produced brave and powerful warriors, so where is that "samurai spirit"?--so to speak. He's making a direct reference to the "manliness" of the Japanese. It's the kind of comment that extreme nationalists who want militarization enjoy. I can imagine they're sitting back thinking "EXACTLY! THANK YOU finally someone says it! we had an army, we fought the mongolians, the koreans, the chinese, why don't we have a military??????" It's the type of direct challenge to one's masculinity that makes someone react in a knee-jerk fashion. I think he might either have been genuinely surprised that Japan is not being aggressive, or he's taunting the Japanese and insulting their sense of masculinity and pride. Either one would not surprise me
