Japanese people are very polite; they will not contradict a guest no matter how much they may disagree. This can easily lead to misunderstanding–when a Japanese host says yes, yes, the meaning may be NO, NO. Foreigners often won’t understand.
Doubtless Japanese and American diplomats understand this and other cultural differences between Americans and Japanese. Hopefully Prime Minister Abe does, but what about President Trump? If Trump hears yes when it means NO, he may be misled at the time and later feel that he was lied to. That’s dangerous. When Trump suggested that Japan shoot down Korean missiles, Abe may have known better but wouldn’t have said so.
Years ago I was in Japan with three others. Every day our host sent two cars to take us to the factory. Traffic was heavy, and we thought two cars were wasteful. The four of us suggested they send one car. Yes, yes our host insisted; he said he understood but seemed agitated–he meant NO, NO! The next morning and every morning after there were two cars.
Travel to Asia is draining, cultural differences unnerving, misunderstanding a danger. Discussions in Asian countries are better left to experts while Trump golfs.