The distinction between considering gas warfare and expecting its use

Was poison gas considered before a possible invasion of Japan?

The option was considered, but its use is judged doubtful because of the legacy of First World War gas warfare.

A proposed chemical attack before an invasion of Japan is acknowledged as an option that had been considered. Its eventual use is judged doubtful in this exchange because the experience of gas warfare in the First World War had discouraged decision-makers. The account therefore distinguishes considering an option from expecting it to be carried out.