Read this excerpt from Franklin Delano Roosevelt's "Fireside Chat 19: On the
War with Japan":
And no honest person, today or a thousand years hence,
will be able to suppress a sense of indignation and horror
at the treachery committed by the military dictators of
Japan, under the very shadow of the flag of peace borne
by their special envoys in our midst.
Based on this excerpt, what is most likely the meaning of "indignation"?