The chief of staff of Japan's air force is to be sacked after he claimed the country had been drawn into the second world war by the US and denied it had been an aggressor during its occupations of the Asian mainland.

In an essay entitled "Was Japan an Aggressor Nation?" General Toshio Tamogami claimed that Japan had been provoked by the then US president, Franklin D Roosevelt, and that many of Japan's wartime victims took "a positive view" of its actions.

The claims, made today in an online essay, drew a swift rebuke from senior politicians.

The defence minister, Yasukazu Hamada, said he would dismiss the general immediately. "I think it is improper of the air force chief of staff to publicly state a view that clearly differs from the that of the government," he told reporters.

"It is inappropriate for him to remain in this position and I will swiftly dismiss him."

The prime minister, Taro Aso, a nationalist who has upset Japan's neighbours with ill-judged comments about the war, described Tamogami's views as "inappropriate, even if they were made in a personal capacity".