Read these sentences from a famous speech made by president roosevelt in 1941.

yesterday, december 7th, 1941 – a date which will live in infamy – the united states of america was suddenly and deliberately attacked by naval and air forces of the empire of japan. the united states was at peace with that nation and, at the solicitation of japan, was still in conversation with its government and its emperor looking toward the maintenance of peace in the pacific.
–president franklin d. roosevelt, 1941

to which event was the president referring?