(The Washington Post article breaking the story does not note whether he explained what harmful effects he foresees. If anyone has the text of this letter, or knows where to find it, I would be much obliged.)
Assuming that Ambassador Kato has not added any details to his dire warnings about how this resolution will harm the US-Japan relationship, I renew the question I asked when Ambassador Kato tried to scare the House Foreign Affairs Committee into voting against the resolution: is that a prediction or a threat?
As I noted then, Americans, public and elite alike, are generally sanguine about the state of the US-Japan relationship, and US elites seem to have no problem separating this thorny historical issue from the relationship. So it seems that if there is to be trouble after the passage of this resolution, it will not be emanating from the US. That leaves Japan.
So, Ambassador Kato, which is it? Are you warning that the Japanese government considers this an unfriendly act and will respond in kind? Or are you warning that it will inflame Japanese public opinion and undermine public support for the US-Japan relationship? Both are manageable, indeed, avoidable, if only Tokyo were capable of some perspective on this issue, instead of immediately becoming defensive, attempting to squash the resolution by whatever means necessary, and making dire predictions about worsening US-Japan relations (it must be the fault of those Democrats in Congress!).
Whatever the case may be, if there is one lesson that Americans should draw from this episode, in combination with the Kyuma affair, it is that clearly the US-Japan relationship has a long way to go before it can be called “normal” — and that there are plenty of history issues between the US and Japan that have yet to be properly confronted.