Read the excerpt from Roosevelt’s address to Congress after the attack on Pearl Harbor.

Yesterday, December 7, 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. . . . I ask that the Congress declare that since the unprovoked and dastardly attack by Japan on Sunday, December 7, 1941, a state of war has existed between the United States and the Japanese Empire.

Based on the excerpt, what is the most likely reason Roosevelt used such strong language in this speech?