Japan could expect protection beyond formal neutrality

If a defensive war with the United States went badly for Japan, would Britain mediate a peace that guaranteed Japanese survival?

Japan probably expected Britain to prevent its destruction, even when a one-on-one war did not formally require British entry.

Japan probably expected Britain to prevent an opponent from destroying it. Preserving the alliance partner would remain a British interest during a one-on-one war in which Britain was formally neutral. An opposing power would therefore have to consider whether pushing the war too far would bring Britain in. The answer suggests possible British involvement, without promising a particular mediated settlement or an unconditional guarantee.